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Linux in a Nutshell

This directory of Linux commands is from Linux in a Nutshell, 5th Edition.

Click on any of the 687 commands below to get a description and list of available options. All links in the command summaries point to the online version of the book on Safari Bookshelf.

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objcopy

objcopy [options] infile [outfile]

Copy the contents of the input object file to another file, optionally changing the file format in the process (but not the endian-ness). If outfile is not specified, objcopy creates a temporary file and renames it to infile when the copy is complete, destroying the original input file. The GNU Binary File Descriptor (BFD) library is used to read and write the object files.

Options

--add-section section=file

Add a new section to the output object file with the specified section name and the contents taken from the specified file. Available only for formats that allow arbitrarily named sections.

--alt-machine-code=n

If the output architecture has alternate machine codes, use the nth code instead of the default.

-b n, --byte=n

Copy only every nth byte. Header data is not affected. The value of n can be from 0 to interleave-1, where interleave is specified by -i (default is 4). This option is useful for creating files to program ROM and is typically used with srec as the output format.

-B bfdarch, --binary-architecture=bfdarch

Set the output architecture to bfdarch (e.g., i386) for transforming a raw binary file into an object file. Otherwise, this option is ignored. After the conversion, your program can access data inside the created object file by referencing the special symbols _binary_objfile_start, _binary_objfile_end, and _binary_objfile_size.

--change-addresses=incr, --adjust-vma=incr

Change the VMA and LMA addresses of all sections, plus the start address, by adding incr. Changing section addresses is not supported by all object formats. Sections are not relocated.

--change-leading-char

For object formats that use a special character (such as an underscore) to begin symbols, change the leading character when converting between formats. If the character is the same in both formats, the option has no effect. Otherwise, it adds, removes, or changes the leading character as appropriate for the output format.

--change-section-address section{=|+|-}val,
--adjust-section-vma section{=|+|-}val

Set or change the VMA and LMA addresses of the specified section. With =, set the section address to the specified value; otherwise, add or subtract the value to get the new address.

--change-section-lma section{=|+|-}val

Set or change the LMA address of the specified section. With =, set the section address to the specified value; otherwise, add or subtract the value to get the new address.

--change-section-vma section{=|+|-}val

Set or change the VMA address of the specified section. With =, set the section address to the specified value; otherwise, add or subtract the value to get the new address.

--change-start incr, --adjust-start incr

Add incr to the start address to get a new start address. Not supported by all object formats.

--change-warnings, --adjust-warnings

Issue a warning if the section that is specified in one of the options --change-section-address, --change-section-lma, or --change-section-vma does not exist.

--debugging

Convert debugging information if possible.

-F bfdname, --target=bfdname

Set the binary format for both input and output files to the binary file descriptor name bfdname. No format translation is done. Use the -h option for a list of supported formats for your system.

-g, --strip-debug

Do not copy debugging information.

-G symbol, --keep-global-symbol=symbol

Copy only the specified global symbol, making all other symbols local to the file. May be specified multiple times.

--gap-fill=val

Fill gaps between sections with the specified value; applies to the load address (LMA) of the sections.

-h, --help

Print help information, including a list of supported target object formats, then exit.

-i interleave, --interleave=interleave

Copy one out of every interleave bytes. Use -b to set the byte to copy (default is 4). This option is ignored if -b is not specified.

-I bfdname, --input-target=bfdname

Set the binary file format of the input file using its binary file descriptor name, bfdname.

-j section, --only-section=section

Copy only the specified section. May be specified multiple times.

-K symbol, --keep-symbol=symbol

Copy only the specified symbol from the source file. May be specified multiple times.

--keep-global-symbols=filename

Apply the option --keep-global-symbol to each symbol listed in the specified file. The file should have one symbol per line, with comments beginning with a hash mark (#). May be specified multiple times.

--keep-symbols=file

Apply the option --keep-symbol to each symbol listed in the specified file. The file should have one symbol per line, with comments beginning with a hash mark (#). May be specified multiple times.

-L symbol, --localize-symbol=symbol

Make the specified symbol local. May be specified multiple times.

--localize-symbols=filename

Apply the option --localize-symbol to each symbol listed in the specified file. The file should have one symbol per line, with comments beginning with a hash mark (#). May be specified multiple times.

-N symbol, --strip-symbol=symbol

Do not copy the specified symbol. May be specified multiple times.

--no-change-warnings, --no-adjust-warnings

Do not issue a warning even if the section specified in one of the options --change-section-address, --change-section-lma, or --change-section-vma does not exist.

-O bfdname, --output-target=bfdname

Set the binary file format of the output file using its binary file descriptor name, bfdname. The format srec generates S-records (printable ASCII versions of object files), and binary generates a raw binary file. Use -h for other available formats.

-p, --preserve-dates

Preserve the input file's access and modification dates in the output file.

--pad-to=addr

Pad the output file up to the load address. Use the fill value specified by --gap-fill (default is 0).

-R section, --remove-section=section

Do not copy any section with the specified name. May be specified multiple times.

--redefine-sym old=new

Change the name of the symbol old to new.

--remove-leading-char

If the first character of a global symbol is a special character (such as an underscore) used by the input object file format, remove it. Unlike --change-leading-char, this option always changes the symbol name when appropriate, regardless of the output object format.

--rename-section oldname=newname[,flags]

Rename a section from oldname to newname, optionally also changing the flags to flags.

-S, --strip-all

Do not copy relocation and symbol information.

--set-section-flags section=flags

Set flags for the specified section as a comma-separated string of flag names. Not all flags are meaningful for all object formats. The possible flags are alloc, code, contents, data, debug, load, noload, readonly, rom, and share.

--set-start=val

Set the start address of the new file to the specified value. Not supported by all object formats.

--srec-forceS3

Force all srec output records to be type S3 records.

--srec-len=ival

Set the maximum length of srec output records to the specified value. The length includes the address, data, and crc fields.

--strip-symbols=filename

Apply the option --strip-symbol to each symbol listed in the specified file. The file should have one symbol per line, with comments beginning with a hash mark (#). May be specified multiple times.

--strip-unneeded

Strip all symbols not needed for relocation processing.

-v, --verbose

Run in verbose mode, listing all object files modified; for archives, list all archive members.

-V, --version

Print version information and exit.

-W symbol, --weaken-symbol=symbol

Make the specified symbol weak. May be specified multiple times.

--weaken

Make all global symbols weak.

--weaken-symbols=filename

Apply the option --weaken-symbol to each symbol listed in the specified file. The file should have one symbol per line, with comments beginning with a hash mark (#). May be specified multiple times.

-x, --discard-all

Do not copy nonglobal symbols.

-X, --discard-locals

Do not copy compiler-generated local symbols (usually those starting with L or ..).