# GNU Binary Utilities

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## Introduction

This brief manual contains documentation for the gnu binary utilities (collectively version 2.16.1):

This document is distributed under the terms of the GNU Free Documentation License. A copy of the license is included in the section entitled "GNU Free Documentation License".

Next: nm, Previous: Top, Up: Top

## 1 ar

         ar [-]p[mod [relpos] [count]] archive [member...]
         ar -M [ <mri-script ]

The gnu ar program creates, modifies, and extracts from archives. An archive is a single file holding a collection of other files in a structure that makes it possible to retrieve the original individual files (called members of the archive).

The original files' contents, mode (permissions), timestamp, owner, and group are preserved in the archive, and can be restored on extraction.

gnu ar can maintain archives whose members have names of any length; however, depending on how ar is configured on your system, a limit on member-name length may be imposed for compatibility with archive formats maintained with other tools. If it exists, the limit is often 15 characters (typical of formats related to a.out) or 16 characters (typical of formats related to coff).

ar is considered a binary utility because archives of this sort are most often used as libraries holding commonly needed subroutines.

ar creates an index to the symbols defined in relocatable object modules in the archive when you specify the modifier s. Once created, this index is updated in the archive whenever ar makes a change to its contents (save for the q update operation). An archive with such an index speeds up linking to the library, and allows routines in the library to call each other without regard to their placement in the archive.

You may use nm -s or nm --print-armap to list this index table. If an archive lacks the table, another form of ar called ranlib can be used to add just the table.

gnu ar is designed to be compatible with two different facilities. You can control its activity using command-line options, like the different varieties of ar on Unix systems; or, if you specify the single command-line option -M, you can control it with a script supplied via standard input, like the MRI “librarian” program.

Next: ar scripts, Up: ar

### 1.1 Controlling ar on the Command Line

         ar [-X32_64] [-]p[mod [relpos] [count]] archive [member...]

When you use ar in the Unix style, ar insists on at least two arguments to execute: one keyletter specifying the operation (optionally accompanied by other keyletters specifying modifiers), and the archive name to act on.

Most operations can also accept further member arguments, specifying particular files to operate on.

gnu ar allows you to mix the operation code p and modifier flags mod in any order, within the first command-line argument.

If you wish, you may begin the first command-line argument with a dash.

The p keyletter specifies what operation to execute; it may be any of the following, but you must specify only one of them:

d
  Delete modules from the archive. Specify the names of modules to be deleted as member...; the archive is untouched if you specify no files to delete.

  If you specify the v modifier, ar lists each module as it is deleted.

m
  Use this operation to move members in an archive.

  The ordering of members in an archive can make a difference in how programs are linked using the library, if a symbol is defined in more than one member.

  If no modifiers are used with `m`, any members you name in the member arguments are moved to the end of the archive; you can use the a, b, or i modifiers to move them to a specified place instead.

p
  Print the specified members of the archive, to the standard output file. If the v modifier is specified, show the member name before copying its contents to standard output.

  If you specify no member arguments, all the files in the archive are printed.

q
  Quick append; Historically, add the files member... to the end of archive, without checking for replacement.

  The modifiers a, b, and i do not affect this operation; new members are always placed at the end of the archive.

  The modifier v makes ar list each file as it is appended.

  Since the point of this operation is speed, the archive's symbol table index is not updated, even if it already existed; you can use ar s or ranlib explicitly to update the symbol table index.

  However, too many different systems assume quick append rebuilds the index, so gnu ar implements q as a synonym for r.

r
  Insert the files member... into archive (with replacement). This operation differs from q in that any previously existing members are deleted if their names match those being added.

  If one of the files named in member... does not exist, ar displays an error message, and leaves undisturbed any existing members of the archive matching that name.

  By default, new members are added at the end of the file; but you may use one of the modifiers a, b, or i to request placement relative to some existing member.

  The modifier v used with this operation elicits a line of output for each file inserted, along with one of the letters a or r to indicate whether the file was appended (no old member deleted) or replaced.

t
  Display a table listing the contents of archive, or those of the files listed in member... that are present in the archive. Normally only the member name is shown; if you also want to see the modes (permissions), timestamp, owner, group, and size, you can request that by also specifying the v modifier.

  If you do not specify a member, all files in the archive are listed.

  If there is more than one file with the same name (say, fie) in an archive (say b.a), ar t b.a fie lists only the first instance; to see them all, you must ask for a complete listing—in our example, ar t b.a.

x
  Extract members (named member) from the archive. You can use the v modifier with this operation, to request that ar list each name as it extracts it.

  If you do not specify a member, all files in the archive are extracted.

A number of modifiers (mod) may immediately follow the p keyletter, to specify variations on an operation's behavior:

a
  Add new files after an existing member of the archive. If you use the modifier a, the name of an existing archive member must be present as the relpos argument, before the archive specification.
b
  Add new files before an existing member of the archive. If you use the modifier b, the name of an existing archive member must be present as the relpos argument, before the archive specification. (same as i).
c
  Create the archive. The specified archive is always created if it did not exist, when you request an update. But a warning is issued unless you specify in advance that you expect to create it, by using this modifier.
f
  Truncate names in the archive. gnu ar will normally permit file names of any length. This will cause it to create archives which are not compatible with the native ar program on some systems. If this is a concern, the f modifier may be used to truncate file names when putting them in the archive.
i
  Insert new files before an existing member of the archive. If you use the modifier i, the name of an existing archive member must be present as the relpos argument, before the archive specification. (same as b).
l
  This modifier is accepted but not used.
N
  Uses the count parameter. This is used if there are multiple entries in the archive with the same name. Extract or delete instance count of the given name from the archive.
o
  Preserve the original dates of members when extracting them. If you do not specify this modifier, files extracted from the archive are stamped with the time of extraction.
P
  Use the full path name when matching names in the archive. gnu ar can not create an archive with a full path name (such archives are not POSIX complaint), but other archive creators can. This option will cause gnu ar to match file names using a complete path name, which can be convenient when extracting a single file from an archive created by another tool.
s
  Write an object-file index into the archive, or update an existing one, even if no other change is made to the archive. You may use this modifier flag either with any operation, or alone. Running ar s on an archive is equivalent to running ranlib on it.
S
  Do not generate an archive symbol table. This can speed up building a large library in several steps. The resulting archive can not be used with the linker. In order to build a symbol table, you must omit the S modifier on the last execution of ar, or you must run ranlib on the archive.
u
  Normally, ar r... inserts all files listed into the archive. If you would like to insert only those of the files you list that are newer than existing members of the same names, use this modifier. The u modifier is allowed only for the operation r (replace). In particular, the combination qu is not allowed, since checking the timestamps would lose any speed advantage from the operation q.
v
  This modifier requests the verbose version of an operation. Many operations display additional information, such as filenames processed, when the modifier v is appended.
V
  This modifier shows the version number of ar.

ar ignores an initial option spelt -X32_64, for compatibility with AIX. The behaviour produced by this option is the default for gnu ar. ar does not support any of the other -X options; in particular, it does not support -X32 which is the default for AIX ar.

Previous: ar cmdline, Up: ar

### 1.2 Controlling ar with a Script

         ar -M [ <script ]

If you use the single command-line option -M with ar, you can control its operation with a rudimentary command language. This form of ar operates interactively if standard input is coming directly from a terminal. During interactive use, ar prompts for input (the prompt is AR >), and continues executing even after errors. If you redirect standard input to a script file, no prompts are issued, and ar abandons execution (with a nonzero exit code) on any error.

The ar command language is not designed to be equivalent to the command-line options; in fact, it provides somewhat less control over archives. The only purpose of the command language is to ease the transition to gnu ar for developers who already have scripts written for the MRI “librarian” program.

The syntax for the ar command language is straightforward:

- commands are recognized in upper or lower case; for example, `LIST` is the same as `list`. In the following descriptions, commands are shown in upper case for clarity.
- a single command may appear on each line; it is the first word on the line.
- empty lines are allowed, and have no effect.
- comments are allowed; text after either of the characters * or ; is ignored.
- Whenever you use a list of names as part of the argument to an ar command, you can separate the individual names with either commas or blanks. Commas are shown in the explanations below, for clarity.
- + is used as a line continuation character; if + appears at the end of a line, the text on the following line is considered part of the current command.

Here are the commands you can use in ar scripts, or when using ar interactively. Three of them have special significance:

`OPEN` or `CREATE` specify a current archive, which is a temporary file required for most of the other commands.

`SAVE` commits the changes so far specified by the script. Prior to `SAVE`, commands affect only the temporary copy of the current archive.

`ADDLIB` archive
`ADDLIB` archive`(`module`,` module`, ...` module`)`
  Add all the contents of archive (or, if specified, each named module from archive) to the current archive.

  Requires prior use of `OPEN` or `CREATE`.

`ADDMOD` member`,` member`, ...` member
  Add each named member as a module in the current archive.

  Requires prior use of `OPEN` or `CREATE`.

`CLEAR`
  Discard the contents of the current archive, canceling the effect of any operations since the last `SAVE`. May be executed (with no effect) even if no current archive is specified.
`CREATE` archive
  Creates an archive, and makes it the current archive (required for many other commands). The new archive is created with a temporary name; it is not actually saved as archive until you use `SAVE`. You can overwrite existing archives; similarly, the contents of any existing file named archive will not be destroyed until `SAVE`.
`DELETE` module`,` module`, ...` module
  Delete each listed module from the current archive; equivalent to ar -d archive module ... module.

  Requires prior use of `OPEN` or `CREATE`.

`DIRECTORY` archive`(`module`, ...` module`)`
`DIRECTORY` archive`(`module`, ...` module`)` outputfile
  List each named module present in archive. The separate command `VERBOSE` specifies the form of the output: when verbose output is off, output is like that of ar -t archive module.... When verbose output is on, the listing is like ar -tv archive module....

  Output normally goes to the standard output stream; however, if you specify outputfile as a final argument, ar directs the output to that file.

`END`
  Exit from ar, with a `0` exit code to indicate successful completion. This command does not save the output file; if you have changed the current archive since the last `SAVE` command, those changes are lost.
`EXTRACT` module`,` module`, ...` module
  Extract each named module from the current archive, writing them into the current directory as separate files. Equivalent to ar -x archive module....

  Requires prior use of `OPEN` or `CREATE`.

`LIST`
  Display full contents of the current archive, in “verbose” style regardless of the state of `VERBOSE`. The effect is like ar tv archive. (This single command is a gnu ar enhancement, rather than present for MRI compatibility.)

  Requires prior use of `OPEN` or `CREATE`.

`OPEN` archive
  Opens an existing archive for use as the current archive (required for many other commands). Any changes as the result of subsequent commands will not actually affect archive until you next use `SAVE`.
`REPLACE` module`,` module`, ...` module
  In the current archive, replace each existing module (named in the `REPLACE` arguments) from files in the current working directory. To execute this command without errors, both the file, and the module in the current archive, must exist.

  Requires prior use of `OPEN` or `CREATE`.

`VERBOSE`
  Toggle an internal flag governing the output from `DIRECTORY`. When the flag is on, `DIRECTORY` output matches output from ar -tv ....
`SAVE`
  Commit your changes to the current archive, and actually save it as a file with the name specified in the last `CREATE` or `OPEN` command.

  Requires prior use of `OPEN` or `CREATE`.

Next: objcopy, Previous: ar, Up: Top

## 2 nm

         nm [-a|--debug-syms] [-g|--extern-only]
            [-B] [-C|--demangle[=style]] [-D|--dynamic]
            [-S|--print-size] [-s|--print-armap]
            [-A|-o|--print-file-name][--special-syms]
            [-n|-v|--numeric-sort] [-p|--no-sort]
            [-r|--reverse-sort] [--size-sort] [-u|--undefined-only]
            [-t radix|--radix=radix] [-P|--portability]
            [--target=bfdname] [-fformat|--format=format]
            [--defined-only] [-l|--line-numbers] [--no-demangle]
            [-V|--version] [-X 32_64] [--help]  [objfile...]

gnu nm lists the symbols from object files objfile.... If no object files are listed as arguments, nm assumes the file a.out.

For each symbol, nm shows:

- The symbol value, in the radix selected by options (see below), or hexadecimal by default.
- The symbol type. At least the following types are used; others are, as well, depending on the object file format. If lowercase, the symbol is local; if uppercase, the symbol is global (external).
  `A`
    The symbol's value is absolute, and will not be changed by further linking.
  `B`
    The symbol is in the uninitialized data section (known as BSS).
  `C`
    The symbol is common. Common symbols are uninitialized data. When linking, multiple common symbols may appear with the same name. If the symbol is defined anywhere, the common symbols are treated as undefined references. For more details on common symbols, see the discussion of –warn-common in Linker options (The GNU linker).
  `D`
    The symbol is in the initialized data section.
  `G`
    The symbol is in an initialized data section for small objects. Some object file formats permit more efficient access to small data objects, such as a global int variable as opposed to a large global array.
  `I`
    The symbol is an indirect reference to another symbol. This is a gnu extension to the a.out object file format which is rarely used.
  `N`
    The symbol is a debugging symbol.
  `R`
    The symbol is in a read only data section.
  `S`
    The symbol is in an uninitialized data section for small objects.
  `T`
    The symbol is in the text (code) section.
  `U`
    The symbol is undefined.
  `V`
    The symbol is a weak object. When a weak defined symbol is linked with a normal defined symbol, the normal defined symbol is used with no error. When a weak undefined symbol is linked and the symbol is not defined, the value of the weak symbol becomes zero with no error.
  `W`
    The symbol is a weak symbol that has not been specifically tagged as a weak object symbol. When a weak defined symbol is linked with a normal defined symbol, the normal defined symbol is used with no error. When a weak undefined symbol is linked and the symbol is not defined, the value of the symbol is determined in a system-specific manner without error. On some systems, uppercase indicates that a default value has been specified.
  `-`
    The symbol is a stabs symbol in an a.out object file. In this case, the next values printed are the stabs other field, the stabs desc field, and the stab type. Stabs symbols are used to hold debugging information. For more information, see Stabs (The “stabs” debug format).
  `?`
    The symbol type is unknown, or object file format specific.
- The symbol name.

The long and short forms of options, shown here as alternatives, are equivalent.

-A
-o
--print-file-name
  Precede each symbol by the name of the input file (or archive member) in which it was found, rather than identifying the input file once only, before all of its symbols.
-a
--debug-syms
  Display all symbols, even debugger-only symbols; normally these are not listed.
-B
  The same as --format=bsd (for compatibility with the MIPS nm).
-C
--demangle[=style]
  Decode (demangle) low-level symbol names into user-level names. Besides removing any initial underscore prepended by the system, this makes C++ function names readable. Different compilers have different mangling styles. The optional demangling style argument can be used to choose an appropriate demangling style for your compiler. See c++filt, for more information on demangling.
--no-demangle
  Do not demangle low-level symbol names. This is the default.
-D
--dynamic
  Display the dynamic symbols rather than the normal symbols. This is only meaningful for dynamic objects, such as certain types of shared libraries.
-f format
--format=format
  Use the output format format, which can be `bsd`, `sysv`, or `posix`. The default is `bsd`. Only the first character of format is significant; it can be either upper or lower case.
-g
--extern-only
  Display only external symbols.
-l
--line-numbers
  For each symbol, use debugging information to try to find a filename and line number. For a defined symbol, look for the line number of the address of the symbol. For an undefined symbol, look for the line number of a relocation entry which refers to the symbol. If line number information can be found, print it after the other symbol information.
-n
-v
--numeric-sort
  Sort symbols numerically by their addresses, rather than alphabetically by their names.
-p
--no-sort
  Do not bother to sort the symbols in any order; print them in the order encountered.
-P
--portability
  Use the POSIX.2 standard output format instead of the default format. Equivalent to -f posix.
-S
--print-size
  Print size, not the value, of defined symbols for the `bsd` output format.
-s
--print-armap
  When listing symbols from archive members, include the index: a mapping (stored in the archive by ar or ranlib) of which modules contain definitions for which names.
-r
--reverse-sort
  Reverse the order of the sort (whether numeric or alphabetic); let the last come first.
--size-sort
  Sort symbols by size. The size is computed as the difference between the value of the symbol and the value of the symbol with the next higher value. If the `bsd` output format is used the size of the symbol is printed, rather than the value, and -S must be used in order both size and value to be printed.
--special-syms
  Display symbols which have a target-specific special meaning. These symbols are usually used by the target for some special processing and are not normally helpful when included included in the normal symbol lists. For example for ARM targets this option would skip the mapping symbols used to mark transistions between ARM code, THUMB code and data.
-t radix
--radix=radix
  Use radix as the radix for printing the symbol values. It must be d for decimal, o for octal, or x for hexadecimal.
--target=bfdname
  Specify an object code format other than your system's default format. See Target Selection, for more information.
-u
--undefined-only
  Display only undefined symbols (those external to each object file).
--defined-only
  Display only defined symbols for each object file.
-V
--version
  Show the version number of nm and exit.
-X
  This option is ignored for compatibility with the AIX version of nm. It takes one parameter which must be the string 32_64. The default mode of AIX nm corresponds to -X 32, which is not supported by gnu nm.
--help
  Show a summary of the options to nm and exit.

Next: objdump, Previous: nm, Up: Top

## 3 objcopy

         objcopy [-F bfdname|--target=bfdname]
                 [-I bfdname|--input-target=bfdname]
                 [-O bfdname|--output-target=bfdname]
                 [-B bfdarch|--binary-architecture=bfdarch]
                 [-S|--strip-all]
                 [-g|--strip-debug]
                 [-K symbolname|--keep-symbol=symbolname]
                 [-N symbolname|--strip-symbol=symbolname]
                 [--strip-unneeded-symbol=symbolname]
                 [-G symbolname|--keep-global-symbol=symbolname]
                 [-L symbolname|--localize-symbol=symbolname]
                 [-W symbolname|--weaken-symbol=symbolname]
                 [-w|--wildcard]
                 [-x|--discard-all]
                 [-X|--discard-locals]
                 [-b byte|--byte=byte]
                 [-i interleave|--interleave=interleave]
                 [-j sectionname|--only-section=sectionname]
                 [-R sectionname|--remove-section=sectionname]
                 [-p|--preserve-dates]
                 [--debugging]
                 [--gap-fill=val]
                 [--pad-to=address]
                 [--set-start=val]
                 [--adjust-start=incr]
                 [--change-addresses=incr]
                 [--change-section-address section{=,+,-}val]
                 [--change-section-lma section{=,+,-}val]
                 [--change-section-vma section{=,+,-}val]
                 [--change-warnings] [--no-change-warnings]
                 [--set-section-flags section=flags]
                 [--add-section sectionname=filename]
                 [--rename-section oldname=newname[,flags]]
                 [--change-leading-char] [--remove-leading-char]
                 [--srec-len=ival] [--srec-forceS3]
                 [--redefine-sym old=new]
                 [--redefine-syms=filename]
                 [--weaken]
                 [--keep-symbols=filename]
                 [--strip-symbols=filename]
                 [--strip-unneeded-symbols=filename]
                 [--keep-global-symbols=filename]
                 [--localize-symbols=filename]
                 [--weaken-symbols=filename]
                 [--alt-machine-code=index]
                 [--prefix-symbols=string]
                 [--prefix-sections=string]
                 [--prefix-alloc-sections=string]
                 [--add-gnu-debuglink=path-to-file]
                 [--only-keep-debug]
                 [--writable-text]
                 [--readonly-text]
                 [--pure]
                 [--impure]
                 [-v|--verbose]
                 [-V|--version]
                 [--help] [--info]
                 infile [outfile]

The gnu objcopy utility copies the contents of an object file to another. objcopy uses the gnu bfd Library to read and write the object files. It can write the destination object file in a format different from that of the source object file. The exact behavior of objcopy is controlled by command-line options. Note that objcopy should be able to copy a fully linked file between any two formats. However, copying a relocatable object file between any two formats may not work as expected.

objcopy creates temporary files to do its translations and deletes them afterward. objcopy uses bfd to do all its translation work; it has access to all the formats described in bfd and thus is able to recognize most formats without being told explicitly. See BFD (Using LD).

objcopy can be used to generate S-records by using an output target of srec (e.g., use -O srec).

objcopy can be used to generate a raw binary file by using an output target of binary (e.g., use -O binary). When objcopy generates a raw binary file, it will essentially produce a memory dump of the contents of the input object file. All symbols and relocation information will be discarded. The memory dump will start at the load address of the lowest section copied into the output file.

When generating an S-record or a raw binary file, it may be helpful to use -S to remove sections containing debugging information. In some cases -R will be useful to remove sections which contain information that is not needed by the binary file.

Note—objcopy is not able to change the endianness of its input files. If the input format has an endianness (some formats do not), objcopy can only copy the inputs into file formats that have the same endianness or which have no endianness (e.g., srec).

infile
outfile
  The input and output files, respectively. If you do not specify outfile, objcopy creates a temporary file and destructively renames the result with the name of infile.
-I bfdname
--input-target=bfdname
  Consider the source file's object format to be bfdname, rather than attempting to deduce it. See Target Selection, for more information.
-O bfdname
--output-target=bfdname
  Write the output file using the object format bfdname. See Target Selection, for more information.
-F bfdname
--target=bfdname
  Use bfdname as the object format for both the input and the output file; i.e., simply transfer data from source to destination with no translation. See Target Selection, for more information.
-B bfdarch
--binary-architecture=bfdarch
  Useful when transforming a raw binary input file into an object file. In this case the output architecture can be set to bfdarch. This option will be ignored if the input file has a known bfdarch. You can access this binary data inside a program by referencing the special symbols that are created by the conversion process. These symbols are called _binary_objfile_start, _binary_objfile_end and _binary_objfile_size. e.g. you can transform a picture file into an object file and then access it in your code using these symbols.
-j sectionname
--only-section=sectionname
  Copy only the named section from the input file to the output file. This option may be given more than once. Note that using this option inappropriately may make the output file unusable.
-R sectionname
--remove-section=sectionname
  Remove any section named sectionname from the output file. This option may be given more than once. Note that using this option inappropriately may make the output file unusable.
-S
--strip-all
  Do not copy relocation and symbol information from the source file.
-g
--strip-debug
  Do not copy debugging symbols or sections from the source file.
--strip-unneeded
  Strip all symbols that are not needed for relocation processing.
-K symbolname
--keep-symbol=symbolname
  Copy only symbol symbolname from the source file. This option may be given more than once.
-N symbolname
--strip-symbol=symbolname
  Do not copy symbol symbolname from the source file. This option may be given more than once.
--strip-unneeded-symbol=symbolname
  Do not copy symbol symbolname from the source file unless it is needed by a relocation. This option may be given more than once.
-G symbolname
--keep-global-symbol=symbolname
  Keep only symbol symbolname global. Make all other symbols local to the file, so that they are not visible externally. This option may be given more than once.
-L symbolname
--localize-symbol=symbolname
  Make symbol symbolname local to the file, so that it is not visible externally. This option may be given more than once.
-W symbolname
--weaken-symbol=symbolname
  Make symbol symbolname weak. This option may be given more than once.
-w
--wildcard
  Permit regular expressions in symbolnames used in other command line options. The question mark (?), asterisk (*), backslash (\) and square brackets ([]) operators can be used anywhere in the symbol name. If the first character of the symbol name is the exclamation point (!) then the sense of the switch is reversed for that symbol. For example:

                  -w -W !foo -W fo*

  would cause objcopy to weaken all symbols that start with “fo” except for the symbol “foo”.

-x
--discard-all
  Do not copy non-global symbols from the source file.
-X
--discard-locals
  Do not copy compiler-generated local symbols. (These usually start with L or ..)
-b byte
--byte=byte
  Keep only every byteth byte of the input file (header data is not affected). byte can be in the range from 0 to interleave-1, where interleave is given by the -i or --interleave option, or the default of 4. This option is useful for creating files to program rom. It is typically used with an `srec` output target.
-i interleave
--interleave=interleave
  Only copy one out of every interleave bytes. Select which byte to copy with the -b or --byte option. The default is 4. objcopy ignores this option if you do not specify either -b or --byte.
-p
--preserve-dates
  Set the access and modification dates of the output file to be the same as those of the input file.
--debugging
  Convert debugging information, if possible. This is not the default because only certain debugging formats are supported, and the conversion process can be time consuming.
--gap-fill val
  Fill gaps between sections with val. This operation applies to the load address (LMA) of the sections. It is done by increasing the size of the section with the lower address, and filling in the extra space created with val.
--pad-to address
  Pad the output file up to the load address address. This is done by increasing the size of the last section. The extra space is filled in with the value specified by --gap-fill (default zero).
--set-start val
  Set the start address of the new file to val. Not all object file formats support setting the start address.
--change-start incr
--adjust-start incr
  Change the start address by adding incr. Not all object file formats support setting the start address.
--change-addresses incr
--adjust-vma incr
  Change the VMA and LMA addresses of all sections, as well as the start address, by adding incr. Some object file formats do not permit section addresses to be changed arbitrarily. Note that this does not relocate the sections; if the program expects sections to be loaded at a certain address, and this option is used to change the sections such that they are loaded at a different address, the program may fail.
--change-section-address section{=,+,-}val
--adjust-section-vma section{=,+,-}val
  Set or change both the VMA address and the LMA address of the named section. If = is used, the section address is set to val. Otherwise, val is added to or subtracted from the section address. See the comments under --change-addresses, above. If section does not exist in the input file, a warning will be issued, unless --no-change-warnings is used.
--change-section-lma section{=,+,-}val
  Set or change the LMA address of the named section. The LMA address is the address where the section will be loaded into memory at program load time. Normally this is the same as the VMA address, which is the address of the section at program run time, but on some systems, especially those where a program is held in ROM, the two can be different. If = is used, the section address is set to val. Otherwise, val is added to or subtracted from the section address. See the comments under --change-addresses, above. If section does not exist in the input file, a warning will be issued, unless --no-change-warnings is used.
--change-section-vma section{=,+,-}val
  Set or change the VMA address of the named section. The VMA address is the address where the section will be located once the program has started executing. Normally this is the same as the LMA address, which is the address where the section will be loaded into memory, but on some systems, especially those where a program is held in ROM, the two can be different. If = is used, the section address is set to val. Otherwise, val is added to or subtracted from the section address. See the comments under --change-addresses, above. If section does not exist in the input file, a warning will be issued, unless --no-change-warnings is used.
--change-warnings
--adjust-warnings
  If --change-section-address or --change-section-lma or --change-section-vma is used, and the named section does not exist, issue a warning. This is the default.
--no-change-warnings
--no-adjust-warnings
  Do not issue a warning if --change-section-address or --adjust-section-lma or --adjust-section-vma is used, even if the named section does not exist.
--set-section-flags section=flags
  Set the flags for the named section. The flags argument is a comma separated string of flag names. The recognized names are alloc, contents, load, noload, readonly, code, data, rom, share, and debug. You can set the contents flag for a section which does not have contents, but it is not meaningful to clear the contents flag of a section which does have contents–just remove the section instead. Not all flags are meaningful for all object file formats.
--add-section sectionname=filename
  Add a new section named sectionname while copying the file. The contents of the new section are taken from the file filename. The size of the section will be the size of the file. This option only works on file formats which can support sections with arbitrary names.
--rename-section oldname=newname[,flags]
  Rename a section from oldname to newname, optionally changing the section's flags to flags in the process. This has the advantage over usng a linker script to perform the rename in that the output stays as an object file and does not become a linked executable.

  This option is particularly helpful when the input format is binary, since this will always create a section called .data. If for example, you wanted instead to create a section called .rodata containing binary data you could use the following command line to achieve it:

                  objcopy -I binary -O <output_format> -B <architecture> \
                   --rename-section .data=.rodata,alloc,load,readonly,data,contents \
                   <input_binary_file> <output_object_file>

--change-leading-char
  Some object file formats use special characters at the start of symbols. The most common such character is underscore, which compilers often add before every symbol. This option tells objcopy to change the leading character of every symbol when it converts between object file formats. If the object file formats use the same leading character, this option has no effect. Otherwise, it will add a character, or remove a character, or change a character, as appropriate.
--remove-leading-char
  If the first character of a global symbol is a special symbol leading character used by the object file format, remove the character. The most common symbol leading character is underscore. This option will remove a leading underscore from all global symbols. This can be useful if you want to link together objects of different file formats with different conventions for symbol names. This is different from --change-leading-char because it always changes the symbol name when appropriate, regardless of the object file format of the output file.
--srec-len=ival
  Meaningful only for srec output. Set the maximum length of the Srecords being produced to ival. This length covers both address, data and crc fields.
--srec-forceS3
  Meaningful only for srec output. Avoid generation of S1/S2 records, creating S3-only record format.
--redefine-sym old=new
  Change the name of a symbol old, to new. This can be useful when one is trying link two things together for which you have no source, and there are name collisions.
--redefine-syms=filename
  Apply --redefine-sym to each symbol pair "old new" listed in the file filename. filename is simply a flat file, with one symbol pair per line. Line comments may be introduced by the hash character. This option may be given more than once.
--weaken
  Change all global symbols in the file to be weak. This can be useful when building an object which will be linked against other objects using the -R option to the linker. This option is only effective when using an object file format which supports weak symbols.
--keep-symbols=filename
  Apply --keep-symbol option to each symbol listed in the file filename. filename is simply a flat file, with one symbol name per line. Line comments may be introduced by the hash character. This option may be given more than once.
--strip-symbols=filename
  Apply --strip-symbol option to each symbol listed in the file filename. filename is simply a flat file, with one symbol name per line. Line comments may be introduced by the hash character. This option may be given more than once.
--strip-unneeded-symbols=filename
  Apply --strip-unneeded-symbol option to each symbol listed in the file filename. filename is simply a flat file, with one symbol name per line. Line comments may be introduced by the hash character. This option may be given more than once.
--keep-global-symbols=filename
  Apply --keep-global-symbol option to each symbol listed in the file filename. filename is simply a flat file, with one symbol name per line. Line comments may be introduced by the hash character. This option may be given more than once.
--localize-symbols=filename
  Apply --localize-symbol option to each symbol listed in the file filename. filename is simply a flat file, with one symbol name per line. Line comments may be introduced by the hash character. This option may be given more than once.
--weaken-symbols=filename
  Apply --weaken-symbol option to each symbol listed in the file filename. filename is simply a flat file, with one symbol name per line. Line comments may be introduced by the hash character. This option may be given more than once.
--alt-machine-code=index
  If the output architecture has alternate machine codes, use the indexth code instead of the default one. This is useful in case a machine is assigned an official code and the tool-chain adopts the new code, but other applications still depend on the original code being used.
--writable-text
  Mark the output text as writable. This option isn't meaningful for all object file formats.
--readonly-text
  Make the output text write protected. This option isn't meaningful for all object file formats.
--pure
  Mark the output file as demand paged. This option isn't meaningful for all object file formats.
--impure
  Mark the output file as impure. This option isn't meaningful for all object file formats.
--prefix-symbols=string
  Prefix all symbols in the output file with string.
--prefix-sections=string
  Prefix all section names in the output file with string.
--prefix-alloc-sections=string
  Prefix all the names of all allocated sections in the output file with string.
--add-gnu-debuglink=path-to-file
  Creates a .gnu_debuglink section which contains a reference to path-to-file and adds it to the output file.
--only-keep-debug
  Strip a file, removing any sections that would be stripped by --strip-debug and leaving the debugging sections.

  The intention is that this option will be used in conjunction with --add-gnu-debuglink to create a two part executable. One a stripped binary which will occupy less space in RAM and in a distribution and the second a debugging information file which is only needed if debugging abilities are required. The suggested procedure to create these files is as follows:

  1. Link the executable as normal. Assuming that is is called `foo` then...
  2. Run `objcopy --only-keep-debug foo foo.dbg` to create a file containing the debugging info.
  3. Run `objcopy --strip-debug foo` to create a stripped executable.
  4. Run `objcopy --add-gnu-debuglink=foo.dbg foo` to add a link to the debugging info into the stripped executable.

  Note - the choice of `.dbg` as an extension for the debug info file is arbitrary. Also the `--only-keep-debug` step is optional. You could instead do this:

  1. Link the executable as normal.
  2. Copy `foo` to `foo.full`
  3. Run `objcopy --strip-debug foo`
  4. Run `objcopy --add-gnu-debuglink=foo.full foo`

  ie the file pointed to by the --add-gnu-debuglink can be the full executable. It does not have to be a file created by the --only-keep-debug switch.

-V
--version
  Show the version number of objcopy.
-v
--verbose
  Verbose output: list all object files modified. In the case of archives, objcopy -V lists all members of the archive.
--help
  Show a summary of the options to objcopy.
--info
  Display a list showing all architectures and object formats available.

Next: ranlib, Previous: objcopy, Up: Top

## 4 objdump

         objdump [-a|--archive-headers]
                 [-b bfdname|--target=bfdname]
                 [-C|--demangle[=style] ]
                 [-d|--disassemble]
                 [-D|--disassemble-all]
                 [-z|--disassemble-zeroes]
                 [-EB|-EL|--endian={big | little }]
                 [-f|--file-headers]
                 [--file-start-context]
                 [-g|--debugging]
                 [-e|--debugging-tags]
                 [-h|--section-headers|--headers]
                 [-i|--info]
                 [-j section|--section=section]
                 [-l|--line-numbers]
                 [-S|--source]
                 [-m machine|--architecture=machine]
                 [-M options|--disassembler-options=options]
                 [-p|--private-headers]
                 [-r|--reloc]
                 [-R|--dynamic-reloc]
                 [-s|--full-contents]
                 [-G|--stabs]
                 [-t|--syms]
                 [-T|--dynamic-syms]
                 [-x|--all-headers]
                 [-w|--wide]
                 [--start-address=address]
                 [--stop-address=address]
                 [--prefix-addresses]
                 [--[no-]show-raw-insn]
                 [--adjust-vma=offset]
                 [--special-syms]
                 [-V|--version]
                 [-H|--help]
                 objfile...

objdump displays information about one or more object files. The options control what particular information to display. This information is mostly useful to programmers who are working on the compilation tools, as opposed to programmers who just want their program to compile and work.

objfile... are the object files to be examined. When you specify archives, objdump shows information on each of the member object files.

The long and short forms of options, shown here as alternatives, are equivalent. At least one option from the list -a,-d,-D,-e,-f,-g,-G,-h,-H,-p,-r,-R,-s,-S,-t,-T,-V,-x must be given.

-a
--archive-header
  If any of the objfile files are archives, display the archive header information (in a format similar to ls -l). Besides the information you could list with ar tv, objdump -a shows the object file format of each archive member.
--adjust-vma=offset
  When dumping information, first add offset to all the section addresses. This is useful if the section addresses do not correspond to the symbol table, which can happen when putting sections at particular addresses when using a format which can not represent section addresses, such as a.out.
-b bfdname
--target=bfdname
  Specify that the object-code format for the object files is bfdname. This option may not be necessary; objdump can automatically recognize many formats.

  For example,

                objdump -b oasys -m vax -h fu.o

  displays summary information from the section headers (-h) of fu.o, which is explicitly identified (-m) as a VAX object file in the format produced by Oasys compilers. You can list the formats available with the -i option. See Target Selection, for more information.

-C
--demangle[=style]
  Decode (demangle) low-level symbol names into user-level names. Besides removing any initial underscore prepended by the system, this makes C++ function names readable. Different compilers have different mangling styles. The optional demangling style argument can be used to choose an appropriate demangling style for your compiler. See c++filt, for more information on demangling.
-g
--debugging
  Display debugging information. This attempts to parse debugging information stored in the file and print it out using a C like syntax. Only certain types of debugging information have been implemented. Some other types are supported by readelf -w. See readelf.
-e
--debugging-tags
  Like -g, but the information is generated in a format compatible with ctags tool.
-d
--disassemble
  Display the assembler mnemonics for the machine instructions from objfile. This option only disassembles those sections which are expected to contain instructions.
-D
--disassemble-all
  Like -d, but disassemble the contents of all sections, not just those expected to contain instructions.
--prefix-addresses
  When disassembling, print the complete address on each line. This is the older disassembly format.
-EB
-EL
--endian={big|little}
  Specify the endianness of the object files. This only affects disassembly. This can be useful when disassembling a file format which does not describe endianness information, such as S-records.
-f
--file-headers
  Display summary information from the overall header of each of the objfile files.
--file-start-context
  Specify that when displaying interlisted source code/disassembly (assumes -S) from a file that has not yet been displayed, extend the context to the start of the file.
-h
--section-headers
--headers
  Display summary information from the section headers of the object file.

  File segments may be relocated to nonstandard addresses, for example by using the -Ttext, -Tdata, or -Tbss options to ld. However, some object file formats, such as a.out, do not store the starting address of the file segments. In those situations, although ld relocates the sections correctly, using objdump -h to list the file section headers cannot show the correct addresses. Instead, it shows the usual addresses, which are implicit for the target.

-H
--help
  Print a summary of the options to objdump and exit.
-i
--info
  Display a list showing all architectures and object formats available for specification with -b or -m.
-j name
--section=name
  Display information only for section name.
-l
--line-numbers
  Label the display (using debugging information) with the filename and source line numbers corresponding to the object code or relocs shown. Only useful with -d, -D, or -r.
-m machine
--architecture=machine
  Specify the architecture to use when disassembling object files. This can be useful when disassembling object files which do not describe architecture information, such as S-records. You can list the available architectures with the -i option.
-M options
--disassembler-options=options
  Pass target specific information to the disassembler. Only supported on some targets. If it is necessary to specify more than one disassembler option then multiple -M options can be used or can be placed together into a comma separated list.

  If the target is an ARM architecture then this switch can be used to select which register name set is used during disassembler. Specifying -M reg-name-std (the default) will select the register names as used in ARM's instruction set documentation, but with register 13 called 'sp', register 14 called 'lr' and register 15 called 'pc'. Specifying -M reg-names-apcs will select the name set used by the ARM Procedure Call Standard, whilst specifying -M reg-names-raw will just use r followed by the register number.

  There are also two variants on the APCS register naming scheme enabled by -M reg-names-atpcs and -M reg-names-special-atpcs which use the ARM/Thumb Procedure Call Standard naming conventions. (Either with the normal register names or the special register names).

  This option can also be used for ARM architectures to force the disassembler to interpret all instructions as Thumb instructions by using the switch --disassembler-options=force-thumb. This can be useful when attempting to disassemble thumb code produced by other compilers.

  For the x86, some of the options duplicate functions of the -m switch, but allow finer grained control. Multiple selections from the following may be specified as a comma separated string. x86-64, i386 and i8086 select disassembly for the given architecture. intel and att select between intel syntax mode and AT&T syntax mode. addr32, addr16, data32 and data16 specify the default address size and operand size. These four options will be overridden if x86-64, i386 or i8086 appear later in the option string. Lastly, suffix, when in AT&T mode, instructs the disassembler to print a mnemonic suffix even when the suffix could be inferred by the operands.

  For PPC, booke, booke32 and booke64 select disassembly of BookE instructions. 32 and 64 select PowerPC and PowerPC64 disassembly, respectively.

  For MIPS, this option controls the printing of instruction mneumonic names and register names in disassembled instructions. Multiple selections from the following may be specified as a comma separated string, and invalid options are ignored:

  `no-aliases`
    Print the 'raw' instruction mneumonic instead of some pseudo instruction mneumonic. I.E. print 'daddu' or 'or' instead of 'move', 'sll' instead of 'nop', etc.
  `gpr-names=`ABI
    Print GPR (general-purpose register) names as appropriate for the specified ABI. By default, GPR names are selected according to the ABI of the binary being disassembled.
  `fpr-names=`ABI
    Print FPR (floating-point register) names as appropriate for the specified ABI. By default, FPR numbers are printed rather than names.
  `cp0-names=`ARCH
    Print CP0 (system control coprocessor; coprocessor 0) register names as appropriate for the CPU or architecture specified by ARCH. By default, CP0 register names are selected according to the architecture and CPU of the binary being disassembled.
  `hwr-names=`ARCH
    Print HWR (hardware register, used by the `rdhwr` instruction) names as appropriate for the CPU or architecture specified by ARCH. By default, HWR names are selected according to the architecture and CPU of the binary being disassembled.
  `reg-names=`ABI
    Print GPR and FPR names as appropriate for the selected ABI.
  `reg-names=`ARCH
    Print CPU-specific register names (CP0 register and HWR names) as appropriate for the selected CPU or architecture.

  For any of the options listed above, ABI or ARCH may be specified as numeric to have numbers printed rather than names, for the selected types of registers. You can list the available values of ABI and ARCH using the --help option.

-p
--private-headers
  Print information that is specific to the object file format. The exact information printed depends upon the object file format. For some object file formats, no additional information is printed.
-r
--reloc
  Print the relocation entries of the file. If used with -d or -D, the relocations are printed interspersed with the disassembly.
-R
--dynamic-reloc
  Print the dynamic relocation entries of the file. This is only meaningful for dynamic objects, such as certain types of shared libraries.
-s
--full-contents
  Display the full contents of any sections requested. By default all non-empty sections are displayed.
-S
--source
  Display source code intermixed with disassembly, if possible. Implies -d.
--show-raw-insn
  When disassembling instructions, print the instruction in hex as well as in symbolic form. This is the default except when --prefix-addresses is used.
--no-show-raw-insn
  When disassembling instructions, do not print the instruction bytes. This is the default when --prefix-addresses is used.
-G
--stabs
  Display the full contents of any sections requested. Display the contents of the .stab and .stab.index and .stab.excl sections from an ELF file. This is only useful on systems (such as Solaris 2.0) in which `.stab` debugging symbol-table entries are carried in an ELF section. In most other file formats, debugging symbol-table entries are interleaved with linkage symbols, and are visible in the --syms output. For more information on stabs symbols, see Stabs (The “stabs” debug format).
--start-address=address
  Start displaying data at the specified address. This affects the output of the -d, -r and -s options.
--stop-address=address
  Stop displaying data at the specified address. This affects the output of the -d, -r and -s options.
-t
--syms
  Print the symbol table entries of the file. This is similar to the information provided by the nm program.
-T
--dynamic-syms
  Print the dynamic symbol table entries of the file. This is only meaningful for dynamic objects, such as certain types of shared libraries. This is similar to the information provided by the nm program when given the -D (--dynamic) option.
--special-syms
  When displaying symbols include those which the target considers to be special in some way and which would not normally be of interest to the user.
-V
--version
  Print the version number of objdump and exit.
-x
--all-headers
  Display all available header information, including the symbol table and relocation entries. Using -x is equivalent to specifying all of -a -f -h -p -r -t.
-w
--wide
  Format some lines for output devices that have more than 80 columns. Also do not truncate symbol names when they are displayed.
-z
--disassemble-zeroes
  Normally the disassembly output will skip blocks of zeroes. This option directs the disassembler to disassemble those blocks, just like any other data.

Next: readelf, Previous: objdump, Up: Top

## 5 ranlib

         ranlib [-vV] archive

ranlib generates an index to the contents of an archive and stores it in the archive. The index lists each symbol defined by a member of an archive that is a relocatable object file.

You may use nm -s or nm --print-armap to list this index.

An archive with such an index speeds up linking to the library and allows routines in the library to call each other without regard to their placement in the archive.

The gnu ranlib program is another form of gnu ar; running ranlib is completely equivalent to executing ar -s. See ar.

-v
-V
--version
  Show the version number of ranlib.

Next: strings, Previous: readelf, Up: Top

## 6 size

         size [-A|-B|--format=compatibility]
              [--help]
              [-d|-o|-x|--radix=number]
              [-t|--totals]
              [--target=bfdname] [-V|--version]
              [objfile...]

The gnu size utility lists the section sizes—and the total size—for each of the object or archive files objfile in its argument list. By default, one line of output is generated for each object file or each module in an archive.

objfile... are the object files to be examined. If none are specified, the file `a.out` will be used.

The command line options have the following meanings:

-A
-B
--format=compatibility
  Using one of these options, you can choose whether the output from gnu size resembles output from System V size (using -A, or --format=sysv), or Berkeley size (using -B, or --format=berkeley). The default is the one-line format similar to Berkeley's.

  Here is an example of the Berkeley (default) format of output from size:

                $ size --format=Berkeley ranlib size
                text    data    bss     dec     hex     filename
                294880  81920   11592   388392  5ed28   ranlib
                294880  81920   11888   388688  5ee50   size

  This is the same data, but displayed closer to System V conventions:

                $ size --format=SysV ranlib size
                ranlib  :
                section         size         addr
                .text         294880         8192
                .data          81920       303104
                .bss           11592       385024
                Total         388392

                size  :
                section         size         addr
                .text         294880         8192
                .data          81920       303104
                .bss           11888       385024
                Total         388688

--help
  Show a summary of acceptable arguments and options.
-d
-o
-x
--radix=number
  Using one of these options, you can control whether the size of each section is given in decimal (-d, or --radix=10); octal (-o, or --radix=8); or hexadecimal (-x, or --radix=16). In --radix=number, only the three values (8, 10, 16) are supported. The total size is always given in two radices; decimal and hexadecimal for -d or -x output, or octal and hexadecimal if you're using -o.
-t
--totals
  Show totals of all objects listed (Berkeley format listing mode only).
--target=bfdname
  Specify that the object-code format for objfile is bfdname. This option may not be necessary; size can automatically recognize many formats. See Target Selection, for more information.
-V
--version
  Display the version number of size.

Next: strip, Previous: size, Up: Top

## 7 strings

         strings [-afov] [-min-len]
                 [-n min-len] [--bytes=min-len]
                 [-t radix] [--radix=radix]
                 [-e encoding] [--encoding=encoding]
                 [-] [--all] [--print-file-name]
                 [--target=bfdname]
                 [--help] [--version] file...

For each file given, gnu strings prints the printable character sequences that are at least 4 characters long (or the number given with the options below) and are followed by an unprintable character. By default, it only prints the strings from the initialized and loaded sections of object files; for other types of files, it prints the strings from the whole file.

strings is mainly useful for determining the contents of non-text files.

-a
--all
-
  Do not scan only the initialized and loaded sections of object files; scan the whole files.
-f
--print-file-name
  Print the name of the file before each string.
--help
  Print a summary of the program usage on the standard output and exit.
-min-len
-n min-len
--bytes=min-len
  Print sequences of characters that are at least min-len characters long, instead of the default 4.
-o
  Like -t o. Some other versions of strings have -o act like -t d instead. Since we can not be compatible with both ways, we simply chose one.
-t radix
--radix=radix
  Print the offset within the file before each string. The single character argument specifies the radix of the offset—o for octal, x for hexadecimal, or d for decimal.
-e encoding
--encoding=encoding
  Select the character encoding of the strings that are to be found. Possible values for encoding are: s = single-7-bit-byte characters (ASCII, ISO 8859, etc., default), S = single-8-bit-byte characters, b = 16-bit bigendian, l = 16-bit littleendian, B = 32-bit bigendian, L = 32-bit littleendian. Useful for finding wide character strings.
--target=bfdname
  Specify an object code format other than your system's default format. See Target Selection, for more information.
-v
--version
  Print the program version number on the standard output and exit.

Next: c++filt, Previous: strings, Up: Top

## 8 strip

         strip [-F bfdname |--target=bfdname]
               [-I bfdname |--input-target=bfdname]
               [-O bfdname |--output-target=bfdname]
               [-s|--strip-all]
               [-S|-g|-d|--strip-debug]
               [-K symbolname |--keep-symbol=symbolname]
               [-N symbolname |--strip-symbol=symbolname]
               [-w|--wildcard]
               [-x|--discard-all] [-X |--discard-locals]
               [-R sectionname |--remove-section=sectionname]
               [-o file] [-p|--preserve-dates]
               [--only-keep-debug]
               [-v |--verbose] [-V|--version]
               [--help] [--info]
               objfile...

gnu strip discards all symbols from object files objfile. The list of object files may include archives. At least one object file must be given.

strip modifies the files named in its argument, rather than writing modified copies under different names.

-F bfdname
--target=bfdname
  Treat the original objfile as a file with the object code format bfdname, and rewrite it in the same format. See Target Selection, for more information.
--help
  Show a summary of the options to strip and exit.
--info
  Display a list showing all architectures and object formats available.
-I bfdname
--input-target=bfdname
  Treat the original objfile as a file with the object code format bfdname. See Target Selection, for more information.
-O bfdname
--output-target=bfdname
  Replace objfile with a file in the output format bfdname. See Target Selection, for more information.
-R sectionname
--remove-section=sectionname
  Remove any section named sectionname from the output file. This option may be given more than once. Note that using this option inappropriately may make the output file unusable.
-s
--strip-all
  Remove all symbols.
-g
-S
-d
--strip-debug
  Remove debugging symbols only.
--strip-unneeded
  Remove all symbols that are not needed for relocation processing.
-K symbolname
--keep-symbol=symbolname
  Keep only symbol symbolname from the source file. This option may be given more than once.
-N symbolname
--strip-symbol=symbolname
  Remove symbol symbolname from the source file. This option may be given more than once, and may be combined with strip options other than -K.
-o file
  Put the stripped output in file, rather than replacing the existing file. When this argument is used, only one objfile argument may be specified.
-p
--preserve-dates
  Preserve the access and modification dates of the file.
-w
--wildcard
  Permit regular expressions in symbolnames used in other command line options. The question mark (?), asterisk (*), backslash (\) and square brackets ([]) operators can be used anywhere in the symbol name. If the first character of the symbol name is the exclamation point (!) then the sense of the switch is reversed for that symbol. For example:

                  -w -K !foo -K fo*

  would cause strip to only keep symbols that start with the letters “fo”, but to discard the symbol “foo”.

-x
--discard-all
  Remove non-global symbols.
-X
--discard-locals
  Remove compiler-generated local symbols. (These usually start with L or ..)
--only-keep-debug
  Strip a file, removing any sections that would be stripped by --strip-debug and leaving the debugging sections.

  The intention is that this option will be used in conjunction with --add-gnu-debuglink to create a two part executable. One a stripped binary which will occupy less space in RAM and in a distribution and the second a debugging information file which is only needed if debugging abilities are required. The suggested procedure to create these files is as follows:

  1. Link the executable as normal. Assuming that is is called `foo` then...
  2. Run `objcopy --only-keep-debug foo foo.dbg` to create a file containing the debugging info.
  3. Run `objcopy --strip-debug foo` to create a stripped executable.
  4. Run `objcopy --add-gnu-debuglink=foo.dbg foo` to add a link to the debugging info into the stripped executable.

  Note - the choice of `.dbg` as an extension for the debug info file is arbitrary. Also the `--only-keep-debug` step is optional. You could instead do this:

  1. Link the executable as normal.
  2. Copy `foo` to `foo.full`
  3. Run `strip --strip-debug foo`
  4. Run `objcopy --add-gnu-debuglink=foo.full foo`

  ie the file pointed to by the --add-gnu-debuglink can be the full executable. It does not have to be a file created by the --only-keep-debug switch.

-V
--version
  Show the version number for strip.
-v
--verbose
  Verbose output: list all object files modified. In the case of archives, strip -v lists all members of the archive.

Next: addr2line, Previous: strip, Up: Top

## 9 c++filt

         c++filt [-_|--strip-underscores]
                 [-j|--java]
                 [-n|--no-strip-underscores]
                 [-p|--no-params]
                 [-s format|--format=format]
                 [--help]  [--version]  [symbol...]

The C++ and Java languages provides function overloading, which means that you can write many functions with the same name (providing each takes parameters of different types). All C++ and Java function names are encoded into a low-level assembly label (this process is known as mangling). The c++filt 1 program does the inverse mapping: it decodes (demangles) low-level names into user-level names so that the linker can keep these overloaded functions from clashing.

Every alphanumeric word (consisting of letters, digits, underscores, dollars, or periods) seen in the input is a potential label. If the label decodes into a C++ name, the C++ name replaces the low-level name in the output.

You can use c++filt to decipher individual symbols:

         c++filt symbol

If no symbol arguments are given, c++filt reads symbol names from the standard input and writes the demangled names to the standard output. All results are printed on the standard output.

-_
--strip-underscores
  On some systems, both the C and C++ compilers put an underscore in front of every name. For example, the C name `foo` gets the low-level name `_foo`. This option removes the initial underscore. Whether c++filt removes the underscore by default is target dependent.
-j
--java
  Prints demangled names using Java syntax. The default is to use C++ syntax.
-n
--no-strip-underscores
  Do not remove the initial underscore.
-p
--no-params
  When demangling the name of a function, do not display the types of the function's parameters.
-s format
--format=format
  c++filt can decode various methods of mangling, used by different compilers. The argument to this option selects which method it uses:
  `auto`
    Automatic selection based on executable (the default method)
  `gnu`
    the one used by the gnu C++ compiler (g++)
  `lucid`
    the one used by the Lucid compiler (lcc)
  `arm`
    the one specified by the C++ Annotated Reference Manual
  `hp`
    the one used by the HP compiler (aCC)
  `edg`
    the one used by the EDG compiler
  `gnu-v3`
    the one used by the gnu C++ compiler (g++) with the V3 ABI.
  `java`
    the one used by the gnu Java compiler (gcj)
  `gnat`
    the one used by the gnu Ada compiler (GNAT).
--help
  Print a summary of the options to c++filt and exit.
--version
  Print the version number of c++filt and exit.

> Warning: c++filt is a new utility, and the details of its user interface are subject to change in future releases. In particular, a command-line option may be required in the the future to decode a name passed as an argument on the command line; in other words,

>               c++filt symbol

> may in a future release become

>               c++filt option symbol

Next: nlmconv, Previous: c++filt, Up: Top

## 10 addr2line

         addr2line [-b bfdname|--target=bfdname]
                   [-C|--demangle[=style]]
                   [-e filename|--exe=filename]
                   [-f|--functions] [-s|--basename]
                   [-H|--help] [-V|--version]
                   [addr addr ...]

addr2line translates program addresses into file names and line numbers. Given an address and an executable, it uses the debugging information in the executable to figure out which file name and line number are associated with a given address.

The executable to use is specified with the -e option. The default is the file a.out.

addr2line has two modes of operation.

In the first, hexadecimal addresses are specified on the command line, and addr2line displays the file name and line number for each address.

In the second, addr2line reads hexadecimal addresses from standard input, and prints the file name and line number for each address on standard output. In this mode, addr2line may be used in a pipe to convert dynamically chosen addresses.

The format of the output is FILENAME:LINENO. The file name and line number for each address is printed on a separate line. If the -f option is used, then each FILENAME:LINENO line is preceded by a FUNCTIONNAME line which is the name of the function containing the address.

If the file name or function name can not be determined, addr2line will print two question marks in their place. If the line number can not be determined, addr2line will print 0.

The long and short forms of options, shown here as alternatives, are equivalent.

-b bfdname
--target=bfdname
  Specify that the object-code format for the object files is bfdname.
-C
--demangle[=style]
  Decode (demangle) low-level symbol names into user-level names. Besides removing any initial underscore prepended by the system, this makes C++ function names readable. Different compilers have different mangling styles. The optional demangling style argument can be used to choose an appropriate demangling style for your compiler. See c++filt, for more information on demangling.
-e filename
--exe=filename
  Specify the name of the executable for which addresses should be translated. The default file is a.out.
-f
--functions
  Display function names as well as file and line number information.
-s
--basenames
  Display only the base of each file name.

Next: windres, Previous: addr2line, Up: Top

## 11 nlmconv

nlmconv converts a relocatable object file into a NetWare Loadable Module.

> Warning: nlmconv is not always built as part of the binary utilities, since it is only useful for NLM targets.

         nlmconv [-I bfdname|--input-target=bfdname]
                 [-O bfdname|--output-target=bfdname]
                 [-T headerfile|--header-file=headerfile]
                 [-d|--debug] [-l linker|--linker=linker]
                 [-h|--help] [-V|--version]
                 infile outfile

nlmconv converts the relocatable i386 object file infile into the NetWare Loadable Module outfile, optionally reading headerfile for NLM header information. For instructions on writing the NLM command file language used in header files, see the linkers section, NLMLINK in particular, of the NLM Development and Tools Overview, which is part of the NLM Software Developer's Kit (“NLM SDK”), available from Novell, Inc. nlmconv uses the gnu Binary File Descriptor library to read infile; see BFD (Using LD), for more information.

nlmconv can perform a link step. In other words, you can list more than one object file for input if you list them in the definitions file (rather than simply specifying one input file on the command line). In this case, nlmconv calls the linker for you.

-I bfdname
--input-target=bfdname
  Object format of the input file. nlmconv can usually determine the format of a given file (so no default is necessary). See Target Selection, for more information.
-O bfdname
--output-target=bfdname
  Object format of the output file. nlmconv infers the output format based on the input format, e.g. for a i386 input file the output format is nlm32-i386. See Target Selection, for more information.
-T headerfile
--header-file=headerfile
  Reads headerfile for NLM header information. For instructions on writing the NLM command file language used in header files, see see the linkers section, of the NLM Development and Tools Overview, which is part of the NLM Software Developer's Kit, available from Novell, Inc.
-d
--debug
  Displays (on standard error) the linker command line used by nlmconv.
-l linker
--linker=linker
  Use linker for any linking. linker can be an absolute or a relative pathname.
-h
--help
  Prints a usage summary.
-V
--version
  Prints the version number for nlmconv.

Next: dlltool, Previous: nlmconv, Up: Top

## 12 windres

windres may be used to manipulate Windows resources.

> Warning: windres is not always built as part of the binary utilities, since it is only useful for Windows targets.

         windres [options] [input-file] [output-file]

windres reads resources from an input file and copies them into an output file. Either file may be in one of three formats:

`rc`
  A text format read by the Resource Compiler.
`res`
  A binary format generated by the Resource Compiler.
`coff`
  A COFF object or executable.

The exact description of these different formats is available in documentation from Microsoft.

When windres converts from the `rc` format to the `res` format, it is acting like the Windows Resource Compiler. When windres converts from the `res` format to the `coff` format, it is acting like the Windows `CVTRES` program.

When windres generates an `rc` file, the output is similar but not identical to the format expected for the input. When an input `rc` file refers to an external filename, an output `rc` file will instead include the file contents.

If the input or output format is not specified, windres will guess based on the file name, or, for the input file, the file contents. A file with an extension of .rc will be treated as an `rc` file, a file with an extension of .res will be treated as a `res` file, and a file with an extension of .o or .exe will be treated as a `coff` file.

If no output file is specified, windres will print the resources in `rc` format to standard output.

The normal use is for you to write an `rc` file, use windres to convert it to a COFF object file, and then link the COFF file into your application. This will make the resources described in the `rc` file available to Windows.

-i filename
--input filename
  The name of the input file. If this option is not used, then windres will use the first non-option argument as the input file name. If there are no non-option arguments, then windres will read from standard input. windres can not read a COFF file from standard input.
-o filename
--output filename
  The name of the output file. If this option is not used, then windres will use the first non-option argument, after any used for the input file name, as the output file name. If there is no non-option argument, then windres will write to standard output. windres can not write a COFF file to standard output. Note, for compatability with rc the option -fo is also accepted, but its use is not recommended.
-J format
--input-format format
  The input format to read. format may be res, rc, or coff. If no input format is specified, windres will guess, as described above.
-O format
--output-format format
  The output format to generate. format may be res, rc, or coff. If no output format is specified, windres will guess, as described above.
-F target
--target target
  Specify the BFD format to use for a COFF file as input or output. This is a BFD target name; you can use the --help option to see a list of supported targets. Normally windres will use the default format, which is the first one listed by the --help option. Target Selection.
--preprocessor program
  When windres reads an `rc` file, it runs it through the C preprocessor first. This option may be used to specify the preprocessor to use, including any leading arguments. The default preprocessor argument is `gcc -E -xc-header -DRC_INVOKED`.
-I directory
--include-dir directory
  Specify an include directory to use when reading an `rc` file. windres will pass this to the preprocessor as an -I option. windres will also search this directory when looking for files named in the `rc` file. If the argument passed to this command matches any of the supported formats (as descrived in the -J option), it will issue a deprecation warning, and behave just like the -J option. New programs should not use this behaviour. If a directory happens to match a format, simple prefix it with ./ to disable the backward compatibility.
-D target
--define sym[=val]
  Specify a -D option to pass to the preprocessor when reading an `rc` file.
-U target
--undefine sym
  Specify a -U option to pass to the preprocessor when reading an `rc` file.
-r
  Ignored for compatibility with rc.
-v
  Enable verbose mode. This tells you what the preprocessor is if you didn't specify one.
-l val
--language val
  Specify the default language to use when reading an `rc` file. val should be a hexadecimal language code. The low eight bits are the language, and the high eight bits are the sublanguage.
--use-temp-file
  Use a temporary file to instead of using popen to read the output of the preprocessor. Use this option if the popen implementation is buggy on the host (eg., certain non-English language versions of Windows 95 and Windows 98 are known to have buggy popen where the output will instead go the console).
--no-use-temp-file
  Use popen, not a temporary file, to read the output of the preprocessor. This is the default behaviour.
-h
--help
  Prints a usage summary.
-V
--version
  Prints the version number for windres.
--yydebug
  If windres is compiled with `YYDEBUG` defined as `1`, this will turn on parser debugging.

Next: Selecting The Target System, Previous: windres, Up: Top

## 13 dlltool

dlltool is used to create the files needed to create dynamic link libraries (DLLs) on systems which understand PE format image files such as Windows. A DLL contains an export table which contains information that the runtime loader needs to resolve references from a referencing program.

The export table is generated by this program by reading in a .def file or scanning the .a and .o files which will be in the DLL. A .o file can contain information in special .drectve sections with export information.

> Note: dlltool is not always built as part of the binary utilities, since it is only useful for those targets which support DLLs.

         dlltool [-d|--input-def def-file-name]
                 [-b|--base-file base-file-name]
                 [-e|--output-exp exports-file-name]
                 [-z|--output-def def-file-name]
                 [-l|--output-lib library-file-name]
                 [--export-all-symbols] [--no-export-all-symbols]
                 [--exclude-symbols list]
                 [--no-default-excludes]
                 [-S|--as path-to-assembler] [-f|--as-flags options]
                 [-D|--dllname name] [-m|--machine machine]
                 [-a|--add-indirect] [-U|--add-underscore] [-k|--kill-at]
                 [-A|--add-stdcall-alias]
                 [-p|--ext-prefix-alias prefix]
                 [-x|--no-idata4] [-c|--no-idata5] [-i|--interwork]
                 [-n|--nodelete] [-t|--temp-prefix prefix]
                 [-v|--verbose]
                 [-h|--help] [-V|--version]
                 [object-file ...]

dlltool reads its inputs, which can come from the -d and -b options as well as object files specified on the command line. It then processes these inputs and if the -e option has been specified it creates a exports file. If the -l option has been specified it creates a library file and if the -z option has been specified it creates a def file. Any or all of the -e, -l and -z options can be present in one invocation of dlltool.

When creating a DLL, along with the source for the DLL, it is necessary to have three other files. dlltool can help with the creation of these files.

The first file is a .def file which specifies which functions are exported from the DLL, which functions the DLL imports, and so on. This is a text file and can be created by hand, or dlltool can be used to create it using the -z option. In this case dlltool will scan the object files specified on its command line looking for those functions which have been specially marked as being exported and put entries for them in the .def file it creates.

In order to mark a function as being exported from a DLL, it needs to have an -export:<name_of_function> entry in the .drectve section of the object file. This can be done in C by using the asm() operator:

           asm (".section .drectve");
           asm (".ascii \"-export:my_func\"");

           int my_func (void) { ... }

The second file needed for DLL creation is an exports file. This file is linked with the object files that make up the body of the DLL and it handles the interface between the DLL and the outside world. This is a binary file and it can be created by giving the -e option to dlltool when it is creating or reading in a .def file.

The third file needed for DLL creation is the library file that programs will link with in order to access the functions in the DLL. This file can be created by giving the -l option to dlltool when it is creating or reading in a .def file.

dlltool builds the library file by hand, but it builds the exports file by creating temporary files containing assembler statements and then assembling these. The -S command line option can be used to specify the path to the assembler that dlltool will use, and the -f option can be used to pass specific flags to that assembler. The -n can be used to prevent dlltool from deleting these temporary assembler files when it is done, and if -n is specified twice then this will prevent dlltool from deleting the temporary object files it used to build the library.

Here is an example of creating a DLL from a source file dll.c and also creating a program (from an object file called program.o) that uses that DLL:

           gcc -c dll.c
           dlltool -e exports.o -l dll.lib dll.o
           gcc dll.o exports.o -o dll.dll
           gcc program.o dll.lib -o program

The command line options have the following meanings:

-d filename
--input-def filename
  Specifies the name of a .def file to be read in and processed.
-b filename
--base-file filename
  Specifies the name of a base file to be read in and processed. The contents of this file will be added to the relocation section in the exports file generated by dlltool.
-e filename
--output-exp filename
  Specifies the name of the export file to be created by dlltool.
-z filename
--output-def filename
  Specifies the name of the .def file to be created by dlltool.
-l filename
--output-lib filename
  Specifies the name of the library file to be created by dlltool.
--export-all-symbols
  Treat all global and weak defined symbols found in the input object files as symbols to be exported. There is a small list of symbols which are not exported by default; see the --no-default-excludes option. You may add to the list of symbols to not export by using the --exclude-symbols option.
--no-export-all-symbols
  Only export symbols explicitly listed in an input .def file or in .drectve sections in the input object files. This is the default behaviour. The .drectve sections are created by dllexport attributes in the source code.
--exclude-symbols list
  Do not export the symbols in list. This is a list of symbol names separated by comma or colon characters. The symbol names should not contain a leading underscore. This is only meaningful when --export-all-symbols is used.
--no-default-excludes
  When --export-all-symbols is used, it will by default avoid exporting certain special symbols. The current list of symbols to avoid exporting is DllMain@12, DllEntryPoint@0, impure_ptr. You may use the --no-default-excludes option to go ahead and export these special symbols. This is only meaningful when --export-all-symbols is used.
-S path
--as path
  Specifies the path, including the filename, of the assembler to be used to create the exports file.
-f options
--as-flags options
  Specifies any specific command line options to be passed to the assembler when building the exports file. This option will work even if the -S option is not used. This option only takes one argument, and if it occurs more than once on the command line, then later occurrences will override earlier occurrences. So if it is necessary to pass multiple options to the assembler they should be enclosed in double quotes.
-D name
--dll-name name
  Specifies the name to be stored in the .def file as the name of the DLL when the -e option is used. If this option is not present, then the filename given to the -e option will be used as the name of the DLL.
-m machine
-machine machine
  Specifies the type of machine for which the library file should be built. dlltool has a built in default type, depending upon how it was created, but this option can be used to override that. This is normally only useful when creating DLLs for an ARM processor, when the contents of the DLL are actually encode using Thumb instructions.
-a
--add-indirect
  Specifies that when dlltool is creating the exports file it should add a section which allows the exported functions to be referenced without using the import library. Whatever the hell that means!
-U
--add-underscore
  Specifies that when dlltool is creating the exports file it should prepend an underscore to the names of the exported functions.
-k
--kill-at
  Specifies that when dlltool is creating the exports file it should not append the string @ <number>. These numbers are called ordinal numbers and they represent another way of accessing the function in a DLL, other than by name.
-A
--add-stdcall-alias
  Specifies that when dlltool is creating the exports file it should add aliases for stdcall symbols without @ <number> in addition to the symbols with @ <number>.
-p
--ext-prefix-alias prefix
  Causes dlltool to create external aliases for all DLL imports with the specified prefix. The aliases are created for both external and import symbols with no leading underscore.
-x
--no-idata4
  Specifies that when dlltool is creating the exports and library files it should omit the `.idata4` section. This is for compatibility with certain operating systems.
-c
--no-idata5
  Specifies that when dlltool is creating the exports and library files it should omit the `.idata5` section. This is for compatibility with certain operating systems.
-i
--interwork
  Specifies that dlltool should mark the objects in the library file and exports file that it produces as supporting interworking between ARM and Thumb code.
-n
--nodelete
  Makes dlltool preserve the temporary assembler files it used to create the exports file. If this option is repeated then dlltool will also preserve the temporary object files it uses to create the library file.
-t prefix
--temp-prefix prefix
  Makes dlltool use prefix when constructing the names of temporary assembler and object files. By default, the temp file prefix is generated from the pid.
-v
--verbose
  Make dlltool describe what it is doing.
-h
--help
  Displays a list of command line options and then exits.
-V
--version
  Displays dlltool's version number and then exits.

Up: dlltool

### 13.1 The format of the dlltool .def file

A .def file contains any number of the following commands:

`NAME` name `[ ,` base `]`
  The result is going to be named name`.exe`.
`LIBRARY` name `[ ,` base `]`
  The result is going to be named name`.dll`.
`EXPORTS ( ( (` name1 `[ =` name2 `] ) | (` name1 `=` module-name `.` external-name `) )`
`[` integer `] [ NONAME ] [ CONSTANT ] [ DATA ] [ PRIVATE ] ) *`
  Declares name1 as an exported symbol from the DLL, with optional ordinal number integer, or declares name1 as an alias (forward) of the function external-name in the DLL module-name.
`IMPORTS ( (` internal-name `=` module-name `.` integer `) | [` internal-name `= ]` module-name `.` external-name `) ) *`
  Declares that external-name or the exported function whose ordinal number is integer is to be imported from the file module-name. If internal-name is specified then this is the name that the imported function will be referred to in the body of the DLL.
`DESCRIPTION` string
  Puts string into the output .exp file in the `.rdata` section.
`STACKSIZE` number-reserve `[,` number-commit `]`
`HEAPSIZE` number-reserve `[,` number-commit `]`
  Generates `--stack` or `--heap` number-reserve,number-commit in the output `.drectve` section. The linker will see this and act upon it.
`CODE` attr `+`
`DATA` attr `+`
`SECTIONS (` section-name attr`+ ) *`
  Generates `--attr` section-name attr in the output `.drectve` section, where attr is one of `READ`, `WRITE`, `EXECUTE` or `SHARED`. The linker will see this and act upon it.

Next: size, Previous: ranlib, Up: Top

## 14 readelf

         readelf [-a|--all]
                 [-h|--file-header]
                 [-l|--program-headers|--segments]
                 [-S|--section-headers|--sections]
                 [-g|--section-groups]
                 [-e|--headers]
                 [-s|--syms|--symbols]
                 [-n|--notes]
                 [-r|--relocs]
                 [-u|--unwind]
                 [-d|--dynamic]
                 [-V|--version-info]
                 [-A|--arch-specific]
                 [-D|--use-dynamic]
                 [-x <number>|--hex-dump=<number>]
                 [-w[liaprmfFsoR]|
                  --debug-dump[=line,=info,=abbrev,=pubnames,=aranges,=macro,=frames,=frames-interp,=str,=loc,=Ranges]]
                 [-I|-histogram]
                 [-v|--version]
                 [-W|--wide]
                 [-H|--help]
                 elffile...

readelf displays information about one or more ELF format object files. The options control what particular information to display.

elffile... are the object files to be examined. 32-bit and 64-bit ELF files are supported, as are archives containing ELF files.

This program performs a similar function to objdump but it goes into more detail and it exists independently of the bfd library, so if there is a bug in bfd then readelf will not be affected.

The long and short forms of options, shown here as alternatives, are equivalent. At least one option besides -v or -H must be given.

-a
--all
  Equivalent to specifiying --file-header, --program-headers, --sections, --symbols, --relocs, --dynamic, --notes and --version-info.
-h
--file-header
  Displays the information contained in the ELF header at the start of the file.
-l
--program-headers
--segments
  Displays the information contained in the file's segment headers, if it has any.
-S
--sections
--section-headers
  Displays the information contained in the file's section headers, if it has any.
-g
--section-groups
  Displays the information contained in the file's section groups, if it has any.
-s
--symbols
--syms
  Displays the entries in symbol table section of the file, if it has one.
-e
--headers
  Display all the headers in the file. Equivalent to -h -l -S.
-n
--notes
  Displays the contents of the NOTE segments and/or sections, if any.
-r
--relocs
  Displays the contents of the file's relocation section, if it has one.
-u
--unwind
  Displays the contents of the file's unwind section, if it has one. Only the unwind sections for IA64 ELF files are currently supported.
-d
--dynamic
  Displays the contents of the file's dynamic section, if it has one.
-V
--version-info
  Displays the contents of the version sections in the file, it they exist.
-A
--arch-specific
  Displays architecture-specific information in the file, if there is any.
-D
--use-dynamic
  When displaying symbols, this option makes readelf use the symbol table in the file's dynamic section, rather than the one in the symbols section.
-x <number>
--hex-dump=<number>
  Displays the contents of the indicated section as a hexadecimal dump.
-w[liaprmfFsoR]
--debug-dump[=line,=info,=abbrev,=pubnames,=aranges,=macro,=frames,=frames-interp,=str,=loc,=Ranges]
  Displays the contents of the debug sections in the file, if any are present. If one of the optional letters or words follows the switch then only data found in those specific sections will be dumped.
-I
--histogram
  Display a histogram of bucket list lengths when displaying the contents of the symbol tables.
-v
--version
  Display the version number of readelf.
-W
--wide
  Don't break output lines to fit into 80 columns. By default readelf breaks section header and segment listing lines for 64-bit ELF files, so that they fit into 80 columns. This option causes readelf to print each section header resp. each segment one a single line, which is far more readable on terminals wider than 80 columns.
-H
--help
  Display the command line options understood by readelf.

Next: Reporting Bugs, Previous: dlltool, Up: Top

## 15 Selecting the Target System

You can specify two aspects of the target system to the gnu binary file utilities, each in several ways:

- the target
- the architecture

In the following summaries, the lists of ways to specify values are in order of decreasing precedence. The ways listed first override those listed later.

The commands to list valid values only list the values for which the programs you are running were configured. If they were configured with --enable-targets=all, the commands list most of the available values, but a few are left out; not all targets can be configured in at once because some of them can only be configured native (on hosts with the same type as the target system).

Next: Architecture Selection, Up: Selecting The Target System

### 15.1 Target Selection

A target is an object file format. A given target may be supported for multiple architectures (see Architecture Selection). A target selection may also have variations for different operating systems or architectures.

The command to list valid target values is objdump -i (the first column of output contains the relevant information).

Some sample values are: a.out-hp300bsd, ecoff-littlemips, a.out-sunos-big.

You can also specify a target using a configuration triplet. This is the same sort of name that is passed to configure to specify a target. When you use a configuration triplet as an argument, it must be fully canonicalized. You can see the canonical version of a triplet by running the shell script config.sub which is included with the sources.

Some sample configuration triplets are: m68k-hp-bsd, mips-dec-ultrix, sparc-sun-sunos.

#### objdump Target

Ways to specify:

1. command line option: -b or --target
2. environment variable `GNUTARGET`
3. deduced from the input file

#### objcopy and strip Input Target

Ways to specify:

1. command line options: -I or --input-target, or -F or --target
2. environment variable `GNUTARGET`
3. deduced from the input file

#### objcopy and strip Output Target

Ways to specify:

1. command line options: -O or --output-target, or -F or --target
2. the input target (see “objcopy and strip Input Target” above)
3. environment variable `GNUTARGET`
4. deduced from the input file

#### nm, size, and strings Target

Ways to specify:

1. command line option: --target
2. environment variable `GNUTARGET`
3. deduced from the input file

Previous: Target Selection, Up: Selecting The Target System

### 15.2 Architecture Selection

An architecture is a type of cpu on which an object file is to run. Its name may contain a colon, separating the name of the processor family from the name of the particular cpu.

The command to list valid architecture values is objdump -i (the second column contains the relevant information).

Sample values: m68k:68020, mips:3000, sparc.

#### objdump Architecture

Ways to specify:

1. command line option: -m or --architecture
2. deduced from the input file

#### objcopy, nm, size, strings Architecture

Ways to specify:

1. deduced from the input file

Next: GNU Free Documentation License, Previous: Selecting The Target System, Up: Top

## 16 Reporting Bugs

Your bug reports play an essential role in making the binary utilities reliable.

Reporting a bug may help you by bringing a solution to your problem, or it may not. But in any case the principal function of a bug report is to help the entire community by making the next version of the binary utilities work better. Bug reports are your contribution to their maintenance.

In order for a bug report to serve its purpose, you must include the information that enables us to fix the bug.

Next: Bug Reporting, Up: Reporting Bugs

### 16.1 Have You Found a Bug?

If you are not sure whether you have found a bug, here are some guidelines:

- If a binary utility gets a fatal signal, for any input whatever, that is a bug. Reliable utilities never crash.

- If a binary utility produces an error message for valid input, that is a bug.
- If you are an experienced user of binary utilities, your suggestions for improvement are welcome in any case.

Previous: Bug Criteria, Up: Reporting Bugs

### 16.2 How to Report Bugs

A number of companies and individuals offer support for gnu products. If you obtained the binary utilities from a support organization, we recommend you contact that organization first.

You can find contact information for many support companies and individuals in the file etc/SERVICE in the gnu Emacs distribution.

In any event, we also recommend that you send bug reports for the binary utilities to bug-binutils@gnu.org.

The fundamental principle of reporting bugs usefully is this: report all the facts. If you are not sure whether to state a fact or leave it out, state it!

Often people omit facts because they think they know what causes the problem and assume that some details do not matter. Thus, you might assume that the name of a file you use in an example does not matter. Well, probably it does not, but one cannot be sure. Perhaps the bug is a stray memory reference which happens to fetch from the location where that pathname is stored in memory; perhaps, if the pathname were different, the contents of that location would fool the utility into doing the right thing despite the bug. Play it safe and give a specific, complete example. That is the easiest thing for you to do, and the most helpful.

Keep in mind that the purpose of a bug report is to enable us to fix the bug if it is new to us. Therefore, always write your bug reports on the assumption that the bug has not been reported previously.

Sometimes people give a few sketchy facts and ask, “Does this ring a bell?” This cannot help us fix a bug, so it is basically useless. We respond by asking for enough details to enable us to investigate. You might as well expedite matters by sending them to begin with.

To enable us to fix the bug, you should include all these things:

- The version of the utility. Each utility announces it if you start it with the --version argument.

  Without this, we will not know whether there is any point in looking for the bug in the current version of the binary utilities.

- Any patches you may have applied to the source, including any patches made to the `BFD` library.
- The type of machine you are using, and the operating system name and version number.
- What compiler (and its version) was used to compile the utilities—e.g. “`gcc-2.7`”.
- The command arguments you gave the utility to observe the bug. To guarantee you will not omit something important, list them all. A copy of the Makefile (or the output from make) is sufficient.

  If we were to try to guess the arguments, we would probably guess wrong and then we might not encounter the bug.

- A complete input file, or set of input files, that will reproduce the bug. If the utility is reading an object file or files, then it is generally most helpful to send the actual object files, uuencoded if necessary to get them through the mail system. Note that bug-binutils@gnu.org is a mailing list, so you should avoid sending very large files to it. Making the files available for anonymous FTP is OK.

  If the source files were produced exclusively using gnu programs (e.g., gcc, gas, and/or the gnu ld), then it may be OK to send the source files rather than the object files. In this case, be sure to say exactly what version of gcc, or whatever, was used to produce the object files. Also say how gcc, or whatever, was configured.

- A description of what behavior you observe that you believe is incorrect. For example, “It gets a fatal signal.”

  Of course, if the bug is that the utility gets a fatal signal, then we will certainly notice it. But if the bug is incorrect output, we might not notice unless it is glaringly wrong. You might as well not give us a chance to make a mistake.

  Even if the problem you experience is a fatal signal, you should still say so explicitly. Suppose something strange is going on, such as your copy of the utility is out of synch, or you have encountered a bug in the C library on your system. (This has happened!) Your copy might crash and ours would not. If you told us to expect a crash, then when ours fails to crash, we would know that the bug was not happening for us. If you had not told us to expect a crash, then we would not be able to draw any conclusion from our observations.

- If you wish to suggest changes to the source, send us context diffs, as generated by diff with the -u, -c, or -p option. Always send diffs from the old file to the new file. If you wish to discuss something in the ld source, refer to it by context, not by line number.

  The line numbers in our development sources will not match those in your sources. Your line numbers would convey no useful information to us.

Here are some things that are not necessary:

- A description of the envelope of the bug.

  Often people who encounter a bug spend a lot of time investigating which changes to the input file will make the bug go away and which changes will not affect it.

  This is often time consuming and not very useful, because the way we will find the bug is by running a single example under the debugger with breakpoints, not by pure deduction from a series of examples. We recommend that you save your time for something else.

  Of course, if you can find a simpler example to report instead of the original one, that is a convenience for us. Errors in the output will be easier to spot, running under the debugger will take less time, and so on.

  However, simplification is not vital; if you do not want to do this, report the bug anyway and send us the entire test case you used.

- A patch for the bug.

  A patch for the bug does help us if it is a good one. But do not omit the necessary information, such as the test case, on the assumption that a patch is all we need. We might see problems with your patch and decide to fix the problem another way, or we might not understand it at all.

  Sometimes with programs as complicated as the binary utilities it is very hard to construct an example that will make the program follow a certain path through the code. If you do not send us the example, we will not be able to construct one, so we will not be able to verify that the bug is fixed.

  And if we cannot understand what bug you are trying to fix, or why your patch should be an improvement, we will not install it. A test case will help us to understand.

- A guess about what the bug is or what it depends on.

  Such guesses are usually wrong. Even we cannot guess right about such things without first using the debugger to find the facts.

Next: Index, Previous: Reporting Bugs, Up: Top

## Appendix A GNU Free Documentation License

Version 1.1, March 2000

         Copyright (C) 2000, 2003  Free Software Foundation, Inc.
         59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

         Everyone is permitted to copy and distribute verbatim copies
         of this license document, but changing it is not allowed.

0. PREAMBLE

   The purpose of this License is to make a manual, textbook, or other written document “free” in the sense of freedom: to assure everyone the effective freedom to copy and redistribute it, with or without modifying it, either commercially or noncommercially. Secondarily, this License preserves for the author and publisher a way to get credit for their work, while not being considered responsible for modifications made by others.

   This License is a kind of “copyleft”, which means that derivative works of the document must themselves be free in the same sense. It complements the GNU General Public License, which is a copyleft license designed for free software.

   We have designed this License in order to use it for manuals for free software, because free software needs free documentation: a free program should come with manuals providing the same freedoms that the software does. But this License is not limited to software manuals; it can be used for any textual work, regardless of subject matter or whether it is published as a printed book. We recommend this License principally for works whose purpose is instruction or reference.

1. APPLICABILITY AND DEFINITIONS

   This License applies to any manual or other work that contains a notice placed by the copyright holder saying it can be distributed under the terms of this License. The “Document”, below, refers to any such manual or work. Any member of the public is a licensee, and is addressed as “you.”

   A “Modified Version” of the Document means any work containing the Document or a portion of it, either copied verbatim, or with modifications and/or translated into another language.

   A “Secondary Section” is a named appendix or a front-matter section of the Document that deals exclusively with the relationship of the publishers or authors of the Document to the Document's overall subject (or to related matters) and contains nothing that could fall directly within that overall subject. (For example, if the Document is in part a textbook of mathematics, a Secondary Section may not explain any mathematics.) The relationship could be a matter of historical connection with the subject or with related matters, or of legal, commercial, philosophical, ethical or political position regarding them.

   The “Invariant Sections” are certain Secondary Sections whose titles are designated, as being those of Invariant Sections, in the notice that says that the Document is released under this License.

   The “Cover Texts” are certain short passages of text that are listed, as Front-Cover Texts or Back-Cover Texts, in the notice that says that the Document is released under this License.

   A “Transparent” copy of the Document means a machine-readable copy, represented in a format whose specification is available to the general public, whose contents can be viewed and edited directly and straightforwardly with generic text editors or (for images composed of pixels) generic paint programs or (for drawings) some widely available drawing editor, and that is suitable for input to text formatters or for automatic translation to a variety of formats suitable for input to text formatters. A copy made in an otherwise Transparent file format whose markup has been designed to thwart or discourage subsequent modification by readers is not Transparent. A copy that is not “Transparent” is called “Opaque.”

   Examples of suitable formats for Transparent copies include plain ASCII without markup, Texinfo input format, LaTeX input format, SGML or XML using a publicly available DTD, and standard-conforming simple HTML designed for human modification. Opaque formats include PostScript, PDF, proprietary formats that can be read and edited only by proprietary word processors, SGML or XML for which the DTD and/or processing tools are not generally available, and the machine-generated HTML produced by some word processors for output purposes only.

   The “Title Page” means, for a printed book, the title page itself, plus such following pages as are needed to hold, legibly, the material this License requires to appear in the title page. For works in formats which do not have any title page as such, “Title Page” means the text near the most prominent appearance of the work's title, preceding the beginning of the body of the text.

2. VERBATIM COPYING

   You may copy and distribute the Document in any medium, either commercially or noncommercially, provided that this License, the copyright notices, and the license notice saying this License applies to the Document are reproduced in all copies, and that you add no other conditions whatsoever to those of this License. You may not use technical measures to obstruct or control the reading or further copying of the copies you make or distribute. However, you may accept compensation in exchange for copies. If you distribute a large enough number of copies you must also follow the conditions in section 3.

   You may also lend copies, under the same conditions stated above, and you may publicly display copies.

3. COPYING IN QUANTITY

   If you publish printed copies of the Document numbering more than 100, and the Document's license notice requires Cover Texts, you must enclose the copies in covers that carry, clearly and legibly, all these Cover Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on the back cover. Both covers must also clearly and legibly identify you as the publisher of these copies. The front cover must present the full title with all words of the title equally prominent and visible. You may add other material on the covers in addition. Copying with changes limited to the covers, as long as they preserve the title of the Document and satisfy these conditions, can be treated as verbatim copying in other respects.

   If the required texts for either cover are too voluminous to fit legibly, you should put the first ones listed (as many as fit reasonably) on the actual cover, and continue the rest onto adjacent pages.

   If you publish or distribute Opaque copies of the Document numbering more than 100, you must either include a machine-readable Transparent copy along with each Opaque copy, or state in or with each Opaque copy a publicly-accessible computer-network location containing a complete Transparent copy of the Document, free of added material, which the general network-using public has access to download anonymously at no charge using public-standard network protocols. If you use the latter option, you must take reasonably prudent steps, when you begin distribution of Opaque copies in quantity, to ensure that this Transparent copy will remain thus accessible at the stated location until at least one year after the last time you distribute an Opaque copy (directly or through your agents or retailers) of that edition to the public.

   It is requested, but not required, that you contact the authors of the Document well before redistributing any large number of copies, to give them a chance to provide you with an updated version of the Document.

4. MODIFICATIONS

   You may copy and distribute a Modified Version of the Document under the conditions of sections 2 and 3 above, provided that you release the Modified Version under precisely this License, with the Modified Version filling the role of the Document, thus licensing distribution and modification of the Modified Version to whoever possesses a copy of it. In addition, you must do these things in the Modified Version:

   A. Use in the Title Page (and on the covers, if any) a title distinct from that of the Document, and from those of previous versions (which should, if there were any, be listed in the History section of the Document). You may use the same title as a previous version if the original publisher of that version gives permission.
   B. List on the Title Page, as authors, one or more persons or entities responsible for authorship of the modifications in the Modified Version, together with at least five of the principal authors of the Document (all of its principal authors, if it has less than five).
   C. State on the Title page the name of the publisher of the Modified Version, as the publisher.
   D. Preserve all the copyright notices of the Document.
   E. Add an appropriate copyright notice for your modifications adjacent to the other copyright notices.
   F. Include, immediately after the copyright notices, a license notice giving the public permission to use the Modified Version under the terms of this License, in the form shown in the Addendum below.
   G. Preserve in that license notice the full lists of Invariant Sections and required Cover Texts given in the Document's license notice.
   H. Include an unaltered copy of this License.
   I. Preserve the section entitled “History”, and its title, and add to it an item stating at least the title, year, new authors, and publisher of the Modified Version as given on the Title Page. If there is no section entitled “History” in the Document, create one stating the title, year, authors, and publisher of the Document as given on its Title Page, then add an item describing the Modified Version as stated in the previous sentence.
   J. Preserve the network location, if any, given in the Document for public access to a Transparent copy of the Document, and likewise the network locations given in the Document for previous versions it was based on. These may be placed in the “History” section. You may omit a network location for a work that was published at least four years before the Document itself, or if the original publisher of the version it refers to gives permission.
   K. In any section entitled “Acknowledgements” or “Dedications”, preserve the section's title, and preserve in the section all the substance and tone of each of the contributor acknowledgements and/or dedications given therein.
   L. Preserve all the Invariant Sections of the Document, unaltered in their text and in their titles. Section numbers or the equivalent are not considered part of the section titles.
   M. Delete any section entitled “Endorsements.” Such a section may not be included in the Modified Version.
   N. Do not retitle any existing section as “Endorsements” or to conflict in title with any Invariant Section.

   If the Modified Version includes new front-matter sections or appendices that qualify as Secondary Sections and contain no material copied from the Document, you may at your option designate some or all of these sections as invariant. To do this, add their titles to the list of Invariant Sections in the Modified Version's license notice. These titles must be distinct from any other section titles.

   You may add a section entitled “Endorsements”, provided it contains nothing but endorsements of your Modified Version by various parties–for example, statements of peer review or that the text has been approved by an organization as the authoritative definition of a standard.

   You may add a passage of up to five words as a Front-Cover Text, and a passage of up to 25 words as a Back-Cover Text, to the end of the list of Cover Texts in the Modified Version. Only one passage of Front-Cover Text and one of Back-Cover Text may be added by (or through arrangements made by) any one entity. If the Document already includes a cover text for the same cover, previously added by you or by arrangement made by the same entity you are acting on behalf of, you may not add another; but you may replace the old one, on explicit permission from the previous publisher that added the old one.

   The author(s) and publisher(s) of the Document do not by this License give permission to use their names for publicity for or to assert or imply endorsement of any Modified Version.

5. COMBINING DOCUMENTS

   You may combine the Document with other documents released under this License, under the terms defined in section 4 above for modified versions, provided that you include in the combination all of the Invariant Sections of all of the original documents, unmodified, and list them all as Invariant Sections of your combined work in its license notice.

   The combined work need only contain one copy of this License, and multiple identical Invariant Sections may be replaced with a single copy. If there are multiple Invariant Sections with the same name but different contents, make the title of each such section unique by adding at the end of it, in parentheses, the name of the original author or publisher of that section if known, or else a unique number. Make the same adjustment to the section titles in the list of Invariant Sections in the license notice of the combined work.

   In the combination, you must combine any sections entitled “History” in the various original documents, forming one section entitled “History”; likewise combine any sections entitled “Acknowledgements”, and any sections entitled “Dedications.” You must delete all sections entitled “Endorsements.”

6. COLLECTIONS OF DOCUMENTS

   You may make a collection consisting of the Document and other documents released under this License, and replace the individual copies of this License in the various documents with a single copy that is included in the collection, provided that you follow the rules of this License for verbatim copying of each of the documents in all other respects.

   You may extract a single document from such a collection, and distribute it individually under this License, provided you insert a copy of this License into the extracted document, and follow this License in all other respects regarding verbatim copying of that document.

7. AGGREGATION WITH INDEPENDENT WORKS

   A compilation of the Document or its derivatives with other separate and independent documents or works, in or on a volume of a storage or distribution medium, does not as a whole count as a Modified Version of the Document, provided no compilation copyright is claimed for the compilation. Such a compilation is called an “aggregate”, and this License does not apply to the other self-contained works thus compiled with the Document, on account of their being thus compiled, if they are not themselves derivative works of the Document.

   If the Cover Text requirement of section 3 is applicable to these copies of the Document, then if the Document is less than one quarter of the entire aggregate, the Document's Cover Texts may be placed on covers that surround only the Document within the aggregate. Otherwise they must appear on covers around the whole aggregate.

8. TRANSLATION

   Translation is considered a kind of modification, so you may distribute translations of the Document under the terms of section 4. Replacing Invariant Sections with translations requires special permission from their copyright holders, but you may include translations of some or all Invariant Sections in addition to the original versions of these Invariant Sections. You may include a translation of this License provided that you also include the original English version of this License. In case of a disagreement between the translation and the original English version of this License, the original English version will prevail.

9. TERMINATION

   You may not copy, modify, sublicense, or distribute the Document except as expressly provided for under this License. Any other attempt to copy, modify, sublicense or distribute the Document is void, and will automatically terminate your rights under this License. However, parties who have received copies, or rights, from you under this License will not have their licenses terminated so long as such parties remain in full compliance.

10. FUTURE REVISIONS OF THIS LICENSE

    The Free Software Foundation may publish new, revised versions of the GNU Free Documentation License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns. See http://www.gnu.org/copyleft/.

    Each version of the License is given a distinguishing version number. If the Document specifies that a particular numbered version of this License “or any later version” applies to it, you have the option of following the terms and conditions either of that specified version or of any later version that has been published (not as a draft) by the Free Software Foundation. If the Document does not specify a version number of this License, you may choose any version ever published (not as a draft) by the Free Software Foundation.

### ADDENDUM: How to use this License for your documents

To use this License in a document you have written, include a copy of the License in the document and put the following copyright and license notices just after the title page:

         Copyright (C)  year  your name.
         Permission is granted to copy, distribute and/or modify this document
         under the terms of the GNU Free Documentation License, Version 1.1
         or any later version published by the Free Software Foundation;
         with the Invariant Sections being list their titles, with the
         Front-Cover Texts being list, and with the Back-Cover Texts being list.
         A copy of the license is included in the section entitled "GNU
         Free Documentation License."

If you have no Invariant Sections, write “with no Invariant Sections” instead of saying which ones are invariant. If you have no Front-Cover Texts, write “no Front-Cover Texts” instead of “Front-Cover Texts being list”; likewise for Back-Cover Texts.

If your document contains nontrivial examples of program code, we recommend releasing these examples in parallel under your choice of free software license, such as the GNU General Public License, to permit their use in free software.

Previous: GNU Free Documentation License, Up: Top

## Index

- .stab: objdump
- `addr2line`: addr2line
- address to file name and line number: addr2line
- all header information, object file: objdump
- `ar`: ar
- ar compatibility: ar
- architecture: objdump
- architectures available: objdump
- archive contents: ranlib
- archive headers: objdump
- archives: ar
- base files: dlltool
- bug criteria: Bug Criteria
- bug reports: Bug Reporting
- bugs: Reporting Bugs
- bugs, reporting: Bug Reporting
- `c++filt`: c++filt
- changing object addresses: objcopy
- changing section address: objcopy
- changing section LMA: objcopy
- changing section VMA: objcopy
- changing start address: objcopy
- collections of files: ar
- compatibility, ar: ar
- contents of archive: ar cmdline
- crash: Bug Criteria
- creating archives: ar cmdline
- `cxxfilt`: c++filt
- dates in archive: ar cmdline
- debug symbols: objdump
- debugging symbols: nm
- deleting from archive: ar cmdline
- demangling C++ symbols: c++filt
- demangling in nm: nm
- demangling in objdump: addr2line
- demangling in objdump: objdump
- disassembling object code: objdump
- disassembly architecture: objdump
- disassembly endianness: objdump
- disassembly, with source: objdump
- discarding symbols: strip
- DLL: dlltool
- `dlltool`: dlltool
- dynamic relocation entries, in object file: objdump
- dynamic symbol table entries, printing: objdump
- dynamic symbols: nm
- ELF dynamic section information: readelf
- ELF file header information: readelf
- ELF file information: readelf
- ELF notes: readelf
- ELF object file format: objdump
- ELF program header information: readelf
- ELF reloc information: readelf
- ELF section group information: readelf
- ELF section information: readelf
- ELF segment information: readelf
- ELF symbol table information: readelf
- ELF version sections informations: readelf
- endianness: objdump
- error on valid input: Bug Criteria
- external symbols: nm
- extract from archive: ar cmdline
- fatal signal: Bug Criteria
- file name: nm
- header information, all: objdump
- input .def file: dlltool
- input file name: nm
- libraries: ar
- listings strings: strings
- machine instructions: objdump
- moving in archive: ar cmdline
- MRI compatibility, ar: ar scripts
- name duplication in archive: ar cmdline
- name length: ar
- `nm`: nm
- nm compatibility: nm
- nm format: nm
- not writing archive index: ar cmdline
- `objdump`: objdump
- object code format: addr2line
- object code format: strings
- object code format: size
- object code format: objdump
- object code format: nm
- object file header: objdump
- object file information: objdump
- object file sections: objdump
- object formats available: objdump
- operations on archive: ar cmdline
- printing from archive: ar cmdline
- printing strings: strings
- quick append to archive: ar cmdline
- radix for section sizes: size
- `ranlib`: ranlib
- `readelf`: readelf
- relative placement in archive: ar cmdline
- relocation entries, in object file: objdump
- removing symbols: strip
- repeated names in archive: ar cmdline
- replacement in archive: ar cmdline
- reporting bugs: Reporting Bugs
- scripts, ar: ar scripts
- section addresses in objdump: objdump
- section headers: objdump
- section information: objdump
- section sizes: size
- sections, full contents: objdump
- `size`: size
- size display format: size
- size number format: size
- sorting symbols: nm
- source code context: objdump
- source disassembly: objdump
- source file name: nm
- source filenames for object files: objdump
- stab: objdump
- start-address: objdump
- stop-address: objdump
- `strings`: strings
- strings, printing: strings
- `strip`: strip
- symbol index: ranlib
- symbol index: ar
- symbol index, listing: nm
- symbol line numbers: nm
- symbol table entries, printing: objdump
- symbols: nm
- symbols, discarding: strip
- undefined symbols: nm
- Unix compatibility, ar: ar cmdline
- unwind information: readelf
- updating an archive: ar cmdline
- version: Top
- VMA in objdump: objdump
- wide output, printing: objdump
- writing archive index: ar cmdline

## Table of Contents

- Introduction
- 1 ar
  - 1.1 Controlling ar on the Command Line
  - 1.2 Controlling ar with a Script
- 2 nm
- 3 objcopy
- 4 objdump
- 5 ranlib
- 6 size
- 7 strings
- 8 strip
- 9 c++filt
- 10 addr2line
- 11 nlmconv
- 12 windres
- 13 dlltool
  - 13.1 The format of the dlltool .def file
- 14 readelf
- 15 Selecting the Target System
  - 15.1 Target Selection
  - 15.2 Architecture Selection
- 16 Reporting Bugs
  - 16.1 Have You Found a Bug?
  - 16.2 How to Report Bugs
- Appendix A GNU Free Documentation License
  - ADDENDUM: How to use this License for your documents
- Index

#### Footnotes

[1] MS-DOS does not allow `+` characters in file names, so on MS-DOS this program is named CXXFILT.