OBJCOPY(1)

💖 NAME 💖

objcopy(1) from GNU Development Tools — bestie, this is the page for objcopy: it does copy and translate object files. That's the whole NAME section, short and iconic. 💅

✨ SYNOPSIS ✨

okay so here's the whole command shape, every option exactly as written, no cap:

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]
        [--strip-unneeded]
        [-K symbolname|--keep-symbol=symbolname]
        [--keep-file-symbols]
        [--keep-section-symbols]
        [-N symbolname|--strip-symbol=symbolname]
        [--strip-unneeded-symbol=symbolname]
        [-G symbolname|--keep-global-symbol=symbolname]
        [--localize-hidden]
        [-L symbolname|--localize-symbol=symbolname]
        [--globalize-symbol=symbolname]
        [--globalize-symbols=filename]
        [-W symbolname|--weaken-symbol=symbolname]
        [-w|--wildcard]
        [-x|--discard-all]
        [-X|--discard-locals]
        [-b byte|--byte=byte]
        [-i [breadth]|--interleave[=breadth]]
        [--interleave-width=width]
        [-j sectionpattern|--only-section=sectionpattern]
        [-R sectionpattern|--remove-section=sectionpattern]
        [--keep-section=sectionpattern]
        [--remove-relocations=sectionpattern]
        [--strip-section-headers]
        [-p|--preserve-dates]
        [-D|--enable-deterministic-archives]
        [-U|--disable-deterministic-archives]
        [--debugging]
        [--gap-fill=val]
        [--pad-to=address]
        [--set-start=val]
        [--adjust-start=incr]
        [--change-addresses=incr]
        [--change-section-address sectionpattern{=,+,-}val]
        [--change-section-lma sectionpattern{=,+,-}val]
        [--change-section-vma sectionpattern{=,+,-}val]
        [--change-warnings] [--no-change-warnings]
        [--set-section-flags sectionpattern=flags]
        [--set-section-alignment sectionpattern=align]
        [--add-section sectionname=filename]
        [--dump-section sectionname=filename]
        [--update-section sectionname=filename]
        [--rename-section oldname=newname[,flags]]
        [--long-section-names {enable,disable,keep}]
        [--change-leading-char] [--remove-leading-char]
        [--reverse-bytes=num]
        [--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]
        [--binary-symbol-prefixstring]
        [--add-symbol name=[section:]value[,flags]]
        [--alt-machine-code=index]
        [--prefix-symbols=string]
        [--prefix-sections=string]
        [--prefix-alloc-sections=string]
        [--add-gnu-debuglink=path-to-file]
        [--only-keep-debug]
        [--strip-dwo]
        [--extract-dwo]
        [--extract-symbol]
        [--writable-text]
        [--readonly-text]
        [--pure]
        [--impure]
        [--file-alignment=num]
        [--heap=reserve[,commit]]
        [--image-base=address]
        [--section-alignment=num]
        [--stack=reserve[,commit]]
        [--subsystem=which:major.minor]
        [--compress-debug-sections]
        [--decompress-debug-sections]
        [--elf-stt-common=val]
        [--merge-notes]
        [--no-merge-notes]
        [--verilog-data-width=val]
        [-v|--verbose]
        [-V|--version]
        [--help] [--info]
        infile [outfile]

🦋 DESCRIPTION 🦋

okay so the GNU objcopy utility copies the contents of an object file to another. It 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.

bestie, listen — 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.

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). (However, see the --reverse-bytes option.)

---

🎀 OPTIONS 🎀

okay bestie, here's the full options list, all the flags, all the details. Lowkey a lot, but we got this. 💪

• 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.
• -O bfdname, --output-target=bfdname — write the output file using the object format bfdname.
• -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.
• -B bfdarch, --binary-architecture=bfdarch — useful when transforming a architecture-less 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 sectionpattern, --only-section=sectionpattern — copy only the indicated sections 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. Wildcard characters are accepted in sectionpattern.

If the first character of sectionpattern is the exclamation point (!) then matching sections will not be copied, even if earlier use of --only-section on the same command line would otherwise copy it. For example:

--only-section=.text.* --only-section=!.text.foo

will copy all sections matching '.text.*' but not the section '.text.foo'.

• -R sectionpattern, --remove-section=sectionpattern — remove any section matching sectionpattern from the output file. This option may be given more than once. Note that using this option inappropriately may make the output file unusable. Wildcard characters are accepted in sectionpattern. Using both the -j and -R options together results in undefined behaviour.

If the first character of sectionpattern is the exclamation point (!) then matching sections will not be removed even if an earlier use of --remove-section on the same command line would otherwise remove it. For example:

--remove-section=.text.* --remove-section=!.text.foo

will remove all sections matching the pattern '.text.*', but will not remove the section '.text.foo'.

• --keep-section=sectionpattern — when removing sections from the output file, keep sections that match sectionpattern.
• --remove-relocations=sectionpattern — remove non-dynamic relocations from the output file for any section matching sectionpattern. This option may be given more than once. Note that using this option inappropriately may make the output file unusable, and attempting to remove a dynamic relocation section such as .rela.plt from an executable or shared library with --remove-relocations=.plt will not work. Wildcard characters are accepted in sectionpattern. For example:

--remove-relocations=.text.*

will remove the relocations for all sections matching the pattern '.text.*'.

If the first character of sectionpattern is the exclamation point (!) then matching sections will not have their relocation removed even if an earlier use of --remove-relocations on the same command line would otherwise cause the relocations to be removed. For example:

--remove-relocations=.text.* --remove-relocations=!.text.foo

will remove all relocations for sections matching the pattern '.text.*', but will not remove relocations for the section '.text.foo'.

• --strip-section-headers — strip section header. This option is specific to ELF files. Implies --strip-all and --merge-notes.
• -S, --strip-all — do not copy relocation and symbol information from the source file. Also deletes debug sections.
• -g, --strip-debug — do not copy debugging symbols or sections from the source file.
• --strip-unneeded — remove all symbols that are not needed for relocation processing in addition to debugging symbols and sections stripped by --strip-debug.
• -K symbolname, --keep-symbol=symbolname — when stripping symbols, keep symbol symbolname even if it would normally be stripped. 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* — keeps only symbolname global, bestie. Every other symbol gets made local to the file so they're not visible externally. You can drop this one multiple times. Note: this one cannot be used together with --globalize-symbol or --globalize-symbols. 💅
• --localize-hidden — in an ELF object, marks every symbol that has hidden or internal visibility as local. This one stacks on top of the symbol-specific localization options like -L.
• -L symbolname, --localize-symbol=*symbolname* — takes a global or weak symbol called symbolname and turns it into a local symbol so it's not visible externally. Can be given more than once. Heads up: unique symbols do not get converted. 🙈
• -W symbolname, --weaken-symbol=*symbolname* — makes symbol symbolname weak. You can give this one more than once too.
• --binary-symbol-prefix=*string* — when it's used with --input-target=binary, this sets string as the base name for the symbols generated for the input file. The symbols are:

<string>_start
<string>_end
<string>_size

By default, the binary input handler derives that prefix from a mangled version of the input file name plus the _binary prefix. This option just lets you say it explicitly. ✨

• --globalize-symbol=*symbolname* — gives symbol symbolname global scoping so it's visible outside of the file where it's defined. Can be given more than once. Note: this one cannot be used together with -G or --keep-global-symbol. 🚫
• -w, --wildcard — unlocks regular expressions in the symbolnames used in other command line options. The ?, *, \ and [] operators can go anywhere in the symbol name. And if the first character of the symbol name is !, the sense of the switch gets reversed for that symbol. Like, for example:

-w -W !foo -W fo*

would make objcopy weaken all symbols that start with "fo" except for the symbol "foo". iykyk 😌

• -x, --discard-all — do not copy non-global symbols from the source file. bye bestie 👋
• -X, --discard-locals — do not copy compiler-generated local symbols. (Those usually start with L or ..) 🗑️
• -b byte, --byte=*byte* — if interleaving got enabled via --interleave, then this is where the range of bytes to keep starts: at the byteth byte. byte can be anywhere from 0 to breadth-1, where breadth is whatever value --interleave was given.
• -i [breadth], --interleave[=*breadth*] — only copies a range out of every breadth bytes. (Header data is not affected, don't worry.) You pick which byte in the range starts the copy with --byte, and you pick the width of the range with --interleave-width.

This one is genuinely so useful for making files to program ROM with. It's typically used with an "srec" output target. Note that objcopy will complain if you don't also specify the --byte option. 😭

The default interleave breadth is 4, so with --byte set to 0, objcopy would copy the first byte out of every four bytes from the input to the output.

• --interleave-width=*width* — when used with --interleave, copies width bytes at a time. The start of the range of bytes to copy is set by --byte, and the extent of the range is set with --interleave.

The default value here is 1. And the value of width plus the byte value set by --byte must not exceed the interleave breadth set by --interleave. ⚠️

You can use this to make images for two 16-bit flashes interleaved in a 32-bit bus by passing -b 0 -i 4 --interleave-width=2 and -b 2 -i 4 --interleave-width=2 to two objcopy commands. If the input was '12345678' then the outputs would be '1256' and '3478' respectively. iconic, honestly 🔥

• -p, --preserve-dates — sets the access and modification dates of the output file to be the same as the input file's.

This one also copies the date stored in a PE format file's header — unless the SOURCE_DATE_EPOCH environment variable is defined. If it is defined, then that variable gets used as the date stored in the header, interpreted as the number of seconds since the Unix epoch. 🕰️

• -D, --enable-deterministic-archives — operate in deterministic mode. When copying archive members and writing the archive index, it uses zero for UIDs, GIDs and timestamps, plus consistent file modes for all files.

If binutils was configured with --enable-deterministic-archives, then this mode is on by default. You can turn it off with the -U option, below. 👑

• -U, --disable-deterministic-archives — do not operate in deterministic mode. This is literally the inverse of -D above: when copying archive members and writing the archive index, it uses their actual UID, GID, timestamp and file mode values.

This is the default unless binutils was configured with --enable-deterministic-archives.

• --debugging — converts debugging information, if possible. It's not the default because only certain debugging formats are supported and the conversion process can be time consuming. ⏳
• --gap-fill val — fills gaps between sections with val. This applies to the load address (LMA) of the sections. It works by increasing the size of the section with the lower address and filling in the extra space it created with val.
• --pad-to address — pads the output file up to the load address address. Done by increasing the size of the last section, and the extra space gets filled in with whatever --gap-fill says (default zero).
• --set-start val — sets the start address (a.k.a. the entry address) of the new file to val. Not all object file formats support setting the start address, just so you know. 🎀
• --change-start incr, --adjust-start incr — changes the start address (a.k.a. the entry address) by adding incr. Again, not all object file formats support setting the start address.
• --change-addresses incr, --adjust-vma incr — changes the VMA and LMA addresses of all sections, plus 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 changes the sections so they load at a different address, the program may fail. 💀

• --change-section-address sectionpattern{=,+,-}val, --adjust-section-vma sectionpattern{=,+,-}val — sets or changes both the VMA address and the LMA address of any section matching sectionpattern. 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 sectionpattern doesn't match any sections in the input file, a warning gets issued — unless --no-change-warnings is used. 😬
• --change-section-lma sectionpattern{=,+,-}val — sets or changes the LMA address of any sections matching sectionpattern. The LMA address is the address where the section will be loaded into memory at program load time. Normally it's the same as the VMA address (which is the address of the section at program run time), but on some systems — especially ones 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 sectionpattern doesn't match any sections in the input file, a warning gets issued, unless --no-change-warnings is used.
• --change-section-vma sectionpattern{=,+,-}val — sets or changes the VMA address of any section matching sectionpattern. The VMA address is where the section will be located once the program has started executing. Normally it's the same as the LMA address (where the section gets loaded into memory), but on some systems — especially ones 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 sectionpattern doesn't match any sections in the input file, a warning gets issued, unless --no-change-warnings is used.

Note — changing the VMA of sections in a fully linked binary can be dangerous, since there may be code that expects the sections to be located at their old address. 🚨

• --change-warnings, --adjust-warnings — if --change-section-address or --change-section-lma or --change-section-vma is used and the section pattern doesn't match any sections, 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 section pattern doesn't match any sections. silence is golden 🤫
• --set-section-flags sectionpattern=flags — sets the flags for any sections matching sectionpattern. The flags argument is a comma separated string of flag names. The recognized names are alloc, contents, load, noload, readonly, code, data, rom, exclude, share, debug, and large.

You can set the contents flag for a section which doesn't have contents, but it's not meaningful to clear the contents flag of a section which does have contents — just remove the section instead, bestie. Not all flags are meaningful for all object file formats. In particular the share flag is only meaningful for COFF format files and not for ELF format files. The ELF x86-64 specific flag large corresponds to SHF_X86_64_LARGE. ✨

• --set-section-alignment sectionpattern=align — sets the alignment for any sections matching sectionpattern. align specifies the alignment in bytes and must be a power of two, i.e. 1, 2, 4, 8.... 🎯

---

⚠️ heads up bestie — the alignment note goes for the option above: setting a section's alignment is not gonna auto-align its LMA or VMA addresses. If those need to move too, you gotta reach for --change-section-lma and/or --change-section-vma. Also lowkey a warning: changing VMAs can cause problems in fully linked binaries where there may be code that expects the contents of the sections to be located at their old address. 💀

• --add-section sectionname=filename — adds a brand-new section called sectionname while it's copying the file, and the contents of that new section come straight from the file filename. The size of the section = the size of the file, periodt. This one only works on file formats that can actually support sections with arbitrary names. Note — you might need to bring --set-section-flags along to set the attributes of the freshly created section, so don't forget her 🎀
• --dump-section sectionname=filename — takes the contents of the section named sectionname and drops them into the file filename, overwriting anything that may have been chilling there previously. This is literally the inverse of --add-section. It's similar to --only-section except it does not create a formatted file — it just dumps the contents as raw binary data, without applying any relocations. You can specify this option more than once 🫶
• --update-section sectionname=filename — replaces the existing contents of a section named sectionname with the contents of file filename. The size of the section gets adjusted to the size of the file. The section flags for sectionname stay unchanged. And for ELF format files the section to segment mapping also remains unchanged — which is something that is not possible using --remove-section followed by --add-section. Yes, that's the whole flex. You can specify this option more than once ✨

💡 note — you can use --rename-section and --update-section to both update and rename a section from one command line. When you do that: pass the original section name to --update-section, and pass the original and new section names to --rename-section. iykyk

• --add-symbol name=[section:]value[,flags] — adds a new symbol named name while copying the file. You can specify this option multiple times. If the section is given, the symbol will be associated with and relative to that section — otherwise it'll be an ABS symbol. Specifying an undefined section will result in a fatal error 😭 and there's no check for the value, it's just taken as specified. Symbol flags can be specified, but not all flags will be meaningful for all object file formats. By default the symbol will be global. The special flag 'before=othersym' will insert the new symbol in front of the specified othersym — otherwise the symbol(s) get added at the end of the symbol table in the order they appear 👑
• --rename-section oldname=newname[,flags] — renames a section from oldname to newname, optionally changing the section's flags to flags in the process. The advantage over using a linker script to do the rename? Your output stays as an object file and does not become a linked executable. She accepts the same set of flags as the --set-section-flags option 🤍

This option is particularly helpful when the input format is binary, since this will always create a section called .data. So if you wanted to instead create a section called .rodata containing binary data, you'd use this 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>

• --long-section-names {enable,disable,keep} — controls the handling of long section names when processing "COFF" and "PE-COFF" object formats. The default behaviour, keep, is to preserve long section names if any are present in the input file. The enable and disable options forcibly enable or disable the use of long section names in the output object — and when disable is in effect, any long section names in the input object will be truncated. The enable option will only emit long section names if any are present in the inputs, which is mostly the same as keep, but it's left undefined whether the enable option might force the creation of an empty string table in the output 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'll 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, so this option will remove a leading underscore from all global symbols. Useful if you wanna 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 🎀
• --reverse-bytes=num — reverses the bytes in a section with output contents. A section length must be evenly divisible by the value given in order for the swap to be able to take place. Reversing takes place before the interleaving is performed.

This option is used typically in generating ROM images for problematic target systems. For example, on some target boards, the 32-bit words fetched from 8-bit ROMs are re-assembled in little-endian byte order regardless of the CPU byte order. Depending on the programming model, the endianness of the ROM may need to be modified 🔥

Picture a simple file with a section containing these eight bytes: 12345678.

Using --reverse-bytes=2 for the above example, the bytes in the output file would be ordered 21436587.

Using --reverse-bytes=4 for the above example, the bytes in the output file would be ordered 43218765.

And by using --reverse-bytes=2 for the above example, followed by --reverse-bytes=4 on the output file, the bytes in the second output file would be ordered 34127856. math is mathing ✨

• --srec-len=ival — meaningful only for srec output. Sets 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. Avoids generation of S1/S2 records, creating S3-only record format 🦋
• --redefine-sym old=new — changes the name of a symbol old, to new. Super useful when you're trying to link two things together for which you have no source, and there are name collisions 😤
• --redefine-syms=filename — applies --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 — changes 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 — applies --keep-symbol 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 — applies --strip-symbol 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 — applies --strip-unneeded-symbol 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 — applies --keep-global-symbol 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 — applies --localize-symbol 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 💖
• --globalize-symbols=filename — applies --globalize-symbol 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. Note: this option cannot be used in conjunction with the -G or --keep-global-symbol options 🙈
• --weaken-symbols=filename — applies --weaken-symbol 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. For ELF based architectures, if the index alternative does not exist then the value is treated as an absolute number to be stored in the e_machine field of the ELF header 👑
• --writable-text — marks the output text as writable. This option isn't meaningful for all object file formats 🤍
• --readonly-text — makes the output text write protected. This option isn't meaningful for all object file formats 💅
• --pure — marks the output file as demand paged ✨. Heads up though: this one isn't meaningful for every object file format, so don't come for me if it does nothing on yours.
• --impure — marks the output file as impure 💅. Same disclaimer bestie: it isn't meaningful for all object file formats.
• --prefix-symbols= string — slaps string on the front of every symbol in the output file. Every single one. Iconic.
• --prefix-sections= string — same energy but for section names: every section name in the output file gets string glued to the front.
• --prefix-alloc-sections= string — and this one only prefixes the names of all the allocated sections in the output file with string. Fancy, selective, we love her.
• --add-gnu-debuglink= path-to-file — makes a .gnu_debuglink section that contains a reference to path-to-file and adds it to the output file 🎀. Note: the file at path-to-file must actually exist. And part of the whole process of adding that .gnu_debuglink section involves embedding a checksum of the contents of the debug info file into the section, so yeah, it needs to be there for real.

So if the debug info file gets built in one location but is gonna be installed later into a different location, do not use the path to the installed location, okay? The --add-gnu-debuglink option will fail because the installed file doesn't exist yet 😭. Instead, put the debug info file in the current directory and use the --add-gnu-debuglink option without any directory components, like this:

objcopy --add-gnu-debuglink=foo.debug

At debug time, the debugger will attempt to look for the separate debug info file in a set of known locations. The exact set of these locations varies depending upon the distribution being used, but it typically includes:

• The same directory as the executable.
• A sub-directory of the directory containing the executable called .debug.
• A global debug directory such as /usr/lib/debug.

As long as the debug info file has been installed into one of these locations before the debugger is run, everything should work correctly 🫶.

• --keep-section-symbols — when you're stripping a file (maybe with --strip-debug or --strip-unneeded), this retains any symbols specifying section names, which would otherwise get stripped. Protective queen behavior 💜.
• --keep-file-symbols — same deal, but for symbols specifying source file names: when stripping (again, think --strip-debug or --strip-unneeded) these get retained instead of stripped. Keeping the receipts fr fr.
• --only-keep-debug — strips a file, removing the contents of any sections that would not be stripped by --strip-debug, and leaves the debugging sections intact. In ELF files, this preserves all note sections in the output 🌸.

Note — the section headers of the stripped sections are preserved, including their sizes, but the contents of the section are discarded. The section headers are preserved so that other tools can match up the debuginfo file with the real executable, even if that executable has been relocated to a different address space.

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 it 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.

i.e., 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 👑.

Note — this switch is only intended for use on fully linked files. It does not make sense to use it on object files where the debugging information may be incomplete. Besides, the gnu_debuglink feature currently only supports the presence of one filename containing debugging information, not multiple filenames on a one-per-object-file basis. So like... don't try it, it's not giving.

• --strip-dwo — removes the contents of all DWARF .dwo sections, leaving the remaining debugging sections and all symbols intact ✨. This option is intended for use by the compiler as part of the -gsplit-dwarf option, which splits debug information between the .o file and a separate .dwo file. The compiler generates all debug information in the same file, then uses the --extract-dwo option to copy the .dwo sections to the .dwo file, then the --strip-dwo option to remove those sections from the original .o file. Teamwork, honestly.
• --extract-dwo — extracts the contents of all DWARF .dwo sections. See the --strip-dwo option above for more info, bestie 🦋.
• --file-alignment num — specifies the file alignment. Sections in the file will always begin at file offsets which are multiples of this number. This defaults to 512. [This option is specific to PE targets.]
• --heap reserve --heap reserve,commit — specifies the number of bytes of memory to reserve (and optionally commit) to be used as heap for this program 🍓. [This option is specific to PE targets.]
• --image-base value — uses value as the base address of your program or dll. This is the lowest memory location that will be used when your program or dll is loaded. To reduce the need to relocate and improve performance of your dlls, each should have a unique base address and not overlap any other dlls 🔥. The default is 0x400000 for executables, and 0x10000000 for dlls. [This option is specific to PE targets.]
• --section-alignment num — [This option is specific to PE targets.]

Sets the section alignment field in the PE header — if one is present in the binary. Sections in memory will always begin at addresses which are a multiple of this number. Defaults to 0x1000.

Note — if a section's LMA or VMA addresses are no longer aligned, and those addresses have not been set via the --set-section-lma or --set-section-vma options, and the file has been fully relocated, then a warning message will be issued ⚠️. It will then be up to the user to decide if the LMA and VMA need updating. You're on your own for that one bestie.

• --stack reserve --stack reserve,commit — specifies the number of bytes of memory to reserve (and optionally commit) to be used as stack for this program 🌈. [This option is specific to PE targets.]
• --subsystem which --subsystem which:major --subsystem which:major.minor — specifies the subsystem under which your program will execute 👑. The legal values for which are "native", "windows", "console", "posix", "efi-app", "efi-bsd", "efi-rtd", "sal-rtd", and "xbox". You may optionally set the subsystem version also. Numeric values are also accepted for which. [This option is specific to PE targets.]
• --extract-symbol — keeps the file's section flags and symbols but removes all section data. Specifically, this option:
  • Removes the contents of all sections.
  • Sets the size of every section to zero.
  • Sets the file's start address to zero.

This option is used to build a .sym file for a VxWorks kernel. It can also be a useful way of reducing the size of a --just-symbols linker input file 💅.

• --compress-debug-sections — compresses DWARF debug sections using zlib with SHF_COMPRESSED from the ELF ABI. Note — if compression would actually make a section larger, then it is not compressed, king behavior honestly.
• --compress-debug-sections=none --compress-debug-sections=zlib --compress-debug-sections=zlib-gnu --compress-debug-sections=zlib-gabi --compress-debug-sections=zstd — for ELF files, these options control how DWARF debug sections are compressed 🎀. --compress-debug-sections=none is equivalent to --decompress-debug-sections. --compress-debug-sections=zlib and --compress-debug-sections=zlib-gabi are equivalent to --compress-debug-sections. --compress-debug-sections=zlib-gnu compresses DWARF debug sections using the obsoleted zlib-gnu format — the debug sections are renamed to begin with .zdebug. --compress-debug-sections=zstd compresses DWARF debug sections using zstd. Note — if compression would actually make a section larger, then it is not compressed nor renamed 🫶.
• --decompress-debug-sections — decompresses DWARF debug sections. For a .zdebug section, the original name is restored. Giving it its name back, we love a redemption arc ✨.
• --elf-stt-common=yes --elf-stt-common=no — for ELF files, these options control whether common symbols should be converted to the "STT_COMMON" or "STT_OBJECT" type. --elf-stt-common=yes converts common symbol type to "STT_COMMON". --elf-stt-common=no converts common symbol type to "STT_OBJECT". Pick your fighter 💀.
• --merge-notes --no-merge-notes — for ELF files, attempt (or do not attempt) to reduce the size of any SHT_NOTE type sections by removing duplicate notes 🧚. Yes-merge or no-merge, that's the whole vibe.
• -V, --version — shows the version number of objcopy. Iconic.
• --verilog-data-width= bytes — for Verilog output, this option controls the number of bytes converted for each output data element. The input target controls the endianness of the conversion ⭐.
• -v, --verbose — verbose output: lists all object files modified. In the case of archives, objcopy -V lists all members of the archive. (Yes, it says -V there. I'm just the messenger 💅.)
• --help — shows a summary of the options to objcopy. Your little cheat sheet 💖.
• --info — displays a list showing all architectures and object formats available. Window shopping for targets, lowkey fun.
• @ file — reads command-line options from file. The options read are inserted in place of the original @file option. If file does not exist, or cannot be read, then the option will be treated literally, and not removed 🙈.

Options in file are separated by whitespace. A whitespace character may be included in an option by surrounding the entire option in either single or double quotes. Any character (including a backslash) may be included by prefixing the character to be included with a backslash. The file may itself contain additional @file options; any such options will be processed recursively 🌀.

🌸 SEE ALSO 🌸

okay so like, when you're done here and you're still in your unix era (and you will be, bestie, there's no going back 💅), go bother these:

• ld(1) — the linker, aka the one who actually assembles your whole vibe into a final binary. you two are gonna be besties, fr fr 🔗
• objdump(1) — the nosy bestie who reads back everything objcopy wrote and tells you exactly what's inside. icon behaviour 👑
• and the Info entries for binutils — the deep lore, the extended universe, the 4am group chat scroll 😭 if you want the full story, that's where it lives 📚

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🎀 COPYRIGHT 🎀

Copyright (c) 1991-2026 Free Software Foundation, Inc.

okay so the legal bit, and ngl you should read it because it's actually giving generous ✨

permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation — with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. literal queen of sharing 🫶

and a copy of the license is included in the section entitled "GNU Free Documentation License" — so if you need the receipts, they're right there in the back 🌈

like, that's it, that's the whole copyright section — no scary small print, just "take it, remix it, pass it on" energy 💖

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and that's a wrap on OBJCOPY(1) bestie!! you made it all the way to the bottom, which honestly? main character energy 🌟 go copy some objects, slay some sections, and remember: always objdump after you objcopy, iykyk 💜

this was binutils-2.47, dated 2026-09-30 — scream it, frame it, put it on your lock screen 🎀✨🦋