OBJCOPY(1)

✨ objcopy(1) ✨

GNU Development Tools

---

🌸 NAME 🌸

objcopy — copy and translate object files 💅

---

🎀 SYNOPSIS 🎀

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]
        [--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 bestie, listen up 💖 The GNU objcopy utility copies the contents of one object file into another. That's literally the whole vibe. And the way it does it? It uses the GNU BFD Library to read and write those object files — she's connected, she knows everybody.

And here's the iconic part: objcopy can write the destination object file in a format different from the source object file. Glow-up via translation, no cap. The exact behavior is controlled by command-line options — so yeah, you're the main character here, you drive.

🫶 Heads up though: objcopy should be able to copy a fully linked file between any two formats. But copying a relocatable object file between any two formats may not work as expected. She's not a miracle worker, she's a translator.

objcopy creates temporary files to do its translations and deletes them afterward — leave no trace, very demure, very mindful. 🧚 It uses BFD to do all its translation work, and because it has access to all the formats described in BFD, it can recognize most formats without you even telling it. iykyk. ✨

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

objcopy can also 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 — gone, deleted, not invited to the party 💀. 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. Clean it up, bestie 🧹

⚠️ 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 💅

• 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. Destructive rename, she's bold like that 😌

---

• -I bfdname, --input-target=bfdname — treat the source file's object format as bfdname, instead of trying to deduce it herself. No guessing, we're telling her 🎀
• -O bfdname, --output-target=bfdname — write the output file using the object format bfdname. Pick your format, slay ✨
• -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. Same format in, same format out, no drama 🌸
• -B bfdarch, --binary-architecture=bfdarch — useful when transforming an 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 the sections that match sectionpattern. Protective queen 🫶
• --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. Everything must go 🗑️
• -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 the debugging symbols and sections stripped by --strip-debug. Extra thorough, she's committed ✨
• -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. Not this one, she's special 🎀
• -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 — okay so this one says keep ONLY symbolname global. Everything else gets made local to the file, so it's not visible externally. You can drop this option more than once.

Note: this option cannot be used in conjunction with the --globalize-symbol or --globalize-symbols options. Periodt. 💅

• --localize-hidden — in an ELF object, mark all symbols that have hidden or internal visibility as local. This stacks on top of symbol-specific localization options like -L. 🫶
• -L symbolname, --localize-symbol=symbolname — convert a global or weak symbol called symbolname into a local symbol, so it's not visible externally. This option may be given more than once. Note: unique symbols are not converted. 😭
• -W symbolname, --weaken-symbol=symbolname — make symbolname weak. This option may be given more than once. ✨
• --globalize-symbol=symbolname — give symbolname global scoping so it's visible outside the file where it's defined. This option may be given more than once.

Note: this option cannot be used in conjunction with the -G or --keep-global-symbol options. 💀

• -w, --wildcard — permit regular expressions in symbolnames used in other command line options. The ?, *, \ and [] operators can be used anywhere in the symbol name. If the first character of the symbol name is !, 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". Slay. ✨

• -x, --discard-all — do not copy non-global symbols from the source file. Bye. 💀
• -X, --discard-locals — do not copy compiler-generated local symbols. (These usually start with L or ...) 🙈
• -b byte, --byte=byte — if interleaving has been enabled via the --interleave option, then start the range of bytes to keep at the byteth byte. byte can be in the range from 0 to breadth-1, where breadth is the value given by the --interleave option. 🧚
• -i [breadth], --interleave[=breadth] — only copy a range out of every breadth bytes. (Header data is not affected). Select which byte in the range begins the copy with the --byte option. Select the width of the range with the --interleave-width option. This is useful for creating files to program ROM. It's typically used with an "srec" output target.

Note: objcopy will complain if you do not specify the --byte option as well.

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 the --interleave option, copy width bytes at a time. The start of the range of bytes to be copied is set by the --byte option, and the extent of the range is set with the --interleave option. The default value for this option is 1. The value of width plus the byte value set by the --byte option must not exceed the interleave breadth set by the --interleave option. This option can be used to create 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. 🔥
• -p, --preserve-dates — set the access and modification dates of the output file to be the same as those of the input file. This option 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 this variable will be 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, use zero for UIDs, GIDs, timestamps, and use consistent file modes for all files. If binutils was configured with --enable-deterministic-archives, then this mode is on by default. It can be disabled with the -U option, below. 🎀
• -U, --disable-deterministic-archives — do not operate in deterministic mode. This is the inverse of the -D option, above: when copying archive members and writing the archive index, use their actual UID, GID, timestamp, and file mode values. This is the default unless binutils was configured with --enable-deterministic-archives. 🌈
• --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 (also known as the entry 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 (also known as the entry 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 sectionpattern{=,+,-}val, --adjust-section-vma sectionpattern{=,+,-}val — set or change 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 does not match any sections in the input file, a warning will be issued, unless --no-change-warnings is used. 🔥
• --change-section-lma sectionpattern{=,+,-}val — set or change 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 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 sectionpattern does not match any sections in the input file, a warning will be issued, unless --no-change-warnings is used. 🧚
• --change-section-vma sectionpattern{=,+,-}val — set or change the VMA address of any section matching sectionpattern. 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 sectionpattern does not match any sections in the input file, a warning will be 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 does not 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 does not match any sections. 🤫
• --set-section-flags sectionpattern=flags — set 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 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. 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 — set 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....

Note: setting a section's alignment will not automatically align its LMA or VMA addresses. If those need to be changed as well then the --change-section-lma and/or --change-section-vma options should be used. Also note that 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 — bestie, we're adding a whole new section named sectionname while copying the file. 📥 The contents of this fresh section come straight from the file filename. The size of the section will be the size of the file. Heads up though: this only works on file formats that can actually support sections with arbitrary names. And also — you might need to reach for --set-section-flags to set the attributes of the newly created section. Don't forget that part, it'll get ya. 💅
• --dump-section sectionname=filename — okay so this one drops the contents of the section named sectionname into the file filename, and it overwrites whatever was already chilling there. No hesitation, no mercy. 💀 This is literally the inverse of --add-section. It's also similar to the --only-section option, except it doesn't create a formatted file — it just dumps the contents as raw binary data, without applying any relocations. And you can specify it more than once, slay. ✨
• --update-section sectionname=filename — this replaces the existing contents of a section named sectionname with the contents of the file filename. The size of the section gets adjusted to the size of the file. The section flags for sectionname stay exactly the same, untouched, protected. 🫶 For ELF format files, the section to segment mapping also remains unchanged — which is a whole thing you cannot do with --remove-section followed by --add-section. And yep, this option can be specified more than once.

Note — you can use --rename-section and --update-section together to both update and rename a section from one command line. In that case, pass the original section name to --update-section, and the original and new section names to --rename-section. iykyk 🧚

• --add-symbol name=[section:]value[,flags] — adding a brand new symbol named name while copying the file. This option may be specified multiple times, go off. 🔥 If section is given, the symbol will be associated with and relative to that section. Otherwise it'll be an ABS symbol. And listen — specifying an undefined section results in a fatal error, so pls be careful. 💀 There's no check for the value, it will be taken as specified. Symbol flags can be specified, and 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) will be added at the end of the symbol table in the order they appear.
• --rename-section oldname=newname[,flags] — rename a section from oldname to newname, optionally changing the section's flags to flags in the process. The advantage over using a linker script for the rename is that the output stays as an object file and does not become a linked executable. Periodt. This option accepts the same set of flags as the --set-section-flags option.

This is especially helpful when the input format is binary, because that will always create a section called .data. So say you wanted to create a section called .rodata containing binary data instead — you'd use this command line to make it happen:

          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} — this 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. When disable is in effect, any long section names in the input object will be truncated (rip 💀). The enable option will only emit long section names if any are present in the inputs — this 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. Flexible queen. 💅
• --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. Super useful if you wanna link together objects of different file formats with different conventions for symbol names. 🌈 And ngl, 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 — reverse 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 one's 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. It's giving chaos but we handle it. 😭

Consider a simple file with a section containing the following 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.

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.

• --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. S3 and nothing else, main character energy. 👑
• --redefine-sym old=new — change the name of a symbol old, to new. This can be useful when you're trying to 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. Heads up: 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.
• --globalize-symbols=filename — apply --globalize-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.

⚠️ Note: this option cannot be used in conjunction with the -G or --keep-global-symbol options. Pick a lane bestie.

• --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. 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 — 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. (yes it really is just --pure's chaotic twin 😭)
• --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 — bestie, this one slaps a prefix on every single allocated section name in the output file. Every. One. And the prefix is whatever string you hand it. 💅
• --add-gnu-debuglink=path-to-file — makes a .gnu_debuglink section that holds a reference to path-to-file, then yeets it into the output file. Heads up: the file at path-to-file has to actually exist. And part of building that .gnu_debuglink section means embedding a checksum of the debug info file's contents right into the section. 🧚

So here's the tea: if your debug info file gets built in one place but it's gonna be installed somewhere else later, do not use the path to the installed location. --add-gnu-debuglink will literally fail, because the installed file doesn't exist yet. Instead, drop the debug info file in the current directory and use the option with no directory components at all, like this:

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

Later, at debug time, the debugger goes hunting for that separate debug info file in a set of known locations. The exact set depends on which distribution you're on, 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 runs, everything should work correctly. ✨

• --keep-section-symbols — when you're stripping a file (maybe with --strip-debug or --strip-unneeded), this keeps any symbols that specify section names. Those would otherwise get stripped, and we don't want that. 🙈
• --keep-file-symbols — same vibe, different target: when stripping a file (again, maybe --strip-debug or --strip-unneeded), this retains any symbols that specify source file names, which would otherwise get stripped. 👑
• --only-keep-debug — strips a file, removing the contents of any sections that --strip-debug wouldn't strip, while leaving the debugging sections completely intact. For 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 get discarded. Why keep the headers? So other tools can match up the debuginfo file with the real executable, even if that executable has been relocated to a totally different address space. 🦋

The intention is that this option gets used together with --add-gnu-debuglink to create a two-part executable. Part one: a stripped binary that takes up less space in RAM and in a distribution. Part two: a debugging information file that's only needed if you actually want debugging abilities. The suggested procedure to create these files is:

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. 😭

• --strip-dwo — removes the contents of all DWARF .dwo sections, leaving the remaining debugging sections and all symbols intact. This one's meant to be used 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 --extract-dwo to copy the .dwo sections to the .dwo file, then uses --strip-dwo to remove those sections from the original .o file. Clever, honestly. 💅
• --extract-dwo — extracts the contents of all DWARF .dwo sections. Peep the --strip-dwo option for more info. ✨
• --file-alignment num — specify the file alignment. Sections in the file will always begin at file offsets which are multiples of this number. Defaults to 512. [This option is specific to PE targets.] 🎀
• --heap reserve —
• --heap reserve,commit — specify 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 — use 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 — this option will also set the alignment field in each section's flags.

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 you, the user, to decide if the LMA and VMA need updating. 🫶

• --stack reserve —
• --stack reserve,commit — specify 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 too. 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, the option:
  • removes the contents of all sections;
  • sets the size of every section to zero; and
  • 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.

• --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. ✨
• --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".
• --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. 🌸
• -V —
• --version — show the version number of objcopy.
• --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: 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. 🔥
• @file — read 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. 🦋

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🌈 SEE ALSO 🌈

ld(1), objdump(1), and the Info entries for binutils. 🫶

💖 COPYRIGHT 💖

okay bestie, legal moment, but make it cute 🌸

Copyright (c) 1991-2025 Free Software Foundation, Inc.

fr fr, that's a whole lotta years of slaying 💅

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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, with no Front-Cover Texts, and with no Back-Cover Texts. 🎀

A copy of the license is included in the section entitled "GNU Free Documentation License". ✨

no cap, if you're gonna remix this doc, the license is literally right there in that section. read it, bestie, it's giving ✨legally-iconic✨ 📜

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and that's the whole page, bestie!! you made it to the end, main character energy fr 🫶✨

this lil beauty is from binutils-2.44 and it's dated 2025-03-28 💖 go forth and objcopy something iconic 👑🦋