Bear is a tool that generates a compilation database for clang tooling.
The JSON compilation database is used in the clang project to provide information on how a single compilation unit is processed. With this, it is easy to re-run the compilation with alternate programs.
Some build systems natively support the generation of a JSON compilation database. For projects that do not use such build tools, Bear generates the JSON file during the build process.
Bear is packaged for many distributions. Check your distribution's package manager. Alternatively, you can build it from source.
After installation, use it like this:
bear -- <your-build-command>
The output file, compile_commands.json, is saved in the current directory.
For more options, you can check the man page or pass the --help parameter.
Note that if you want to pass parameters to Bear, pass them before the --;
everything after that is considered part of the build command.
Please be aware that some package managers still ship the 2.4.x release. In
that case, please omit the extra -- or consult your local documentation.
For more information, read the man pages or the project wiki, which talks about limitations, known issues, and platform-specific usage.
Use Bear when your build system does not natively support generating a JSON compilation database. If your project already uses CMake, Meson, or Bazel, prefer the built-in compilation database export those tools provide — it will be faster and more reliable.
Bear works on:
- Linux (glibc and musl) — interception via
LD_PRELOAD - macOS — interception via
DYLD_INSERT_LIBRARIES - FreeBSD, NetBSD, OpenBSD, DragonFly BSD — interception via
LD_PRELOAD - Windows — wrapper-based interception only (no preload library)
- macOS System Integrity Protection (SIP) can prevent library preloading for system-protected executables. See the wiki for workarounds.
- Builds that use sandboxing (e.g., Nix, Flatpak) may block interception.
- When using distcc or ccache, Bear may need extra configuration to intercept the actual compiler invocation. Consult the wiki.
- Bear intercepts process creation — builds that do not spawn a compiler process (e.g., some IDE-internal builds) will not produce output.
Bear 3.x and later require a -- separator between Bear flags and the build
command:
bear -- make
Bear 2.4.x does not use the separator:
bear make
Check your installed version with bear --version.
Before opening a new problem report, please check the wiki to see if your problem is a known issue with a documented workaround. It's also helpful to look at older (possibly closed) issues before opening a new one.
If you decide to report a problem, please provide as much context as possible to help reproduce the error. If you just have a question about usage, please don't be shy; ask your question in an issue or in our chat.
If you've found a bug and have a fix for it, please share it by opening a pull request.
Please follow the contribution guide when you do.
