Back to Commands

objcopy

developmentLinux/Unix
The objcopy command is one of the most frequently used commands in Linux/Unix-like operating systems. objcopy Copy and translate object files
See ExamplesView Syntax

Quick Reference

Command Name:

objcopy

Category:

development

Platform:

Linux/Unix

Basic Usage:

objcopy [options] [arguments]

Common Use Cases

    Syntax

    objcopy [options] input-file [output-file]

    Options

    Option Description
    -I bfdname, --input-target=bfdname Set the input file format
    -O bfdname, --output-target=bfdname Set the output file format
    -F bfdname, --target=bfdname Set both input and output formats to bfdname
    -R sectionname, --remove-section=sectionname Remove named section from the output
    -S, --strip-all Remove all symbols and relocation information
    -g, --strip-debug Remove all debugging symbols
    --strip-unneeded Remove all symbols not needed by relocations
    --only-keep-debug Keep only debugging information
    --add-gnu-debuglink=file Add section .gnu_debuglink linking to file
    --add-section=sectionname=filename Add section sectionname with contents from filename
    --rename-section=old=new[,flags] Rename section old to new, optionally setting flags
    --set-section-flags=sectionname=flags Set section flags for named section
    -K symbolname, --keep-symbol=symbolname Keep only symbol symbolname
    -N symbolname, --strip-symbol=symbolname Remove symbol symbolname
    --keep-symbols=filename Keep only symbols listed in filename
    --strip-symbols=filename Remove symbols listed in filename
    --redefine-sym=old=new Rename symbol old to new
    --redefine-syms=filename Rename symbols listed in filename
    --weaken Change all global symbols to weak
    -G symbolname, --keep-global-symbol=symbolname Keep only symbol symbolname global
    -W symbolname, --weaken-symbol=symbolname Make symbol symbolname weak
    --gap-fill=val Fill gaps between sections with val
    --pad-to=address Pad the last section to address
    --compress-debug-sections Compress DWARF debug sections

    Examples

    How to Use These Examples

    The examples below show common ways to use the objcopy command. Try them in your terminal to see the results. You can copy any example by clicking on the code block.

    # Basic Examples Basic
    objcopy -O binary input.o output.bin
    Convert an object file to binary format.
    objcopy --strip-all input.o output.o
    Strip all symbol and relocation information from an object file.
    # Advanced Examples Advanced
    objcopy --only-section=.text input.o text.bin Extract only the .text section from an object file. objcopy --remove-section=.comment input.o output.o Remove the .comment section from an object file. objcopy --add-section=.data=data.raw input.o output.o Add data from a raw binary file as a new section. objcopy --rename-section=.text=.code input.o output.o Rename a section in the object file. objcopy -S --add-gnu-debuglink=debug.o input.o output.o Strip debugging information but add a reference to a separate debug file. objcopy --weaken input.o output.o Convert all global symbols to weak symbols. objcopy --keep-symbols=symbols.list input.o output.o Keep only the symbols listed in the file symbols.list. objcopy --redefine-sym=old=new input.o output.o Rename a specific symbol in the object file.

    Try It Yourself

    Practice makes perfect! The best way to learn is by trying these examples on your own system with real files.

    Understanding Syntax

    Pay attention to the syntax coloring: commands, options, and file paths are highlighted differently.

    Notes

    The objcopy utility is part of the GNU Binutils package and serves as a powerful tool for manipulating object files in various ways. It's primarily designed to copy and translate object files from one format to another, but it provides a wide range of additional functionality for modifying object files during the copy process. As a key component in many build systems and toolchains, objcopy plays a crucial role in embedded systems development, cross-compilation workflows, and software distribution preparation. It's especially valuable in scenarios where you need to extract specific sections from binaries, prepare files for different platforms, or manipulate binary files without recompiling source code. Key features of the objcopy command: 1. Format Conversion: objcopy can convert object files between different formats, such as ELF, COFF, and raw binary. This is particularly useful when targeting different architectures or when preparing files for firmware uploads. 2. Section Manipulation: The utility allows detailed control over sections within object files, including the ability to add, remove, rename, or extract specific sections. This is valuable for creating specialized binary files that contain only the necessary parts of a program. 3. Symbol Table Management: objcopy provides comprehensive capabilities for managing symbol tables, allowing you to strip, keep, rename, or modify symbols in object files. This can be used to reduce file size or prepare libraries for distribution. 4. Debug Information Handling: The tool offers multiple options for handling debug information, including stripping it completely, keeping only debug information, or setting up separate debug files through the GNU debuglink mechanism. 5. Binary Data Integration: objcopy can embed raw binary data (like firmware images, configuration data, or resources) into object files as named sections, making it easier to include non-code data in compiled programs. Common use cases for objcopy include: - Creating binary firmware images from ELF files for embedded systems - Extracting specific sections (like .text or .data) from compiled programs - Reducing binary size by removing unnecessary symbols or debug information - Preparing separate debug files for distribution while keeping the main binary compact - Embedding resource data into executable files - Renaming sections or symbols to resolve conflicts or meet specific requirements - Converting object files between different architectures or binary formats - Creating specialized boot loaders or firmware updates objcopy is often used in combination with other binutils tools like nm, strip, and readelf to perform sophisticated binary file manipulations. It's a fundamental tool for system programmers, embedded developers, and toolchain engineers who need precise control over binary file formats and content. While powerful, objcopy should be used with care, as incorrect modifications to object files can render them unusable or cause subtle runtime issues. It's always advisable to work on copies of original files and validate the results thoroughly.

    Related Commands

    These commands are frequently used alongside objcopy or serve similar purposes:

    objdump
    nm
    readelf
    strip
    ar
    ld
    as
    gcc
    binutils
    Explore All Commands

    Use Cases

    Learn By Doing

    The best way to learn Linux commands is by practicing. Try out these examples in your terminal to build muscle memory and understand how the objcopy command works in different scenarios.

    See ExamplesTry Lab Exercises
    $ objcopy
    View All Commands