Provided by: bear_2.1.5-1_amd64 
NAME
bear - build ear
SYNOPSIS
bear [options] [build commands]
DESCRIPTION
Bear is a tool to generate compilation database for clang tooling.
The JSON compilation database (http://clang.llvm.org/docs/JSONCompilationDatabase.html) is used in clang
project to provide information how a single compilation unit was processed. When that is available then
it is easy to re-run the compilation with different programs.
Bear execs the original build command and intercept the exec calls. To achieve that Bear uses the
LD_PRELOAD or DYLD_INSERT_LIBRARIES mechanisms provided by the dynamic linker. There is a library which
defines the exec methods and used in every child processes of the build command. The executable itself
sets the environment up to child processes and writes the output file.
OPTIONS
-o output, --cdb output
Specify output file. Default value provided.
-a, --append
Use previously generated output file and append the new entries to it. This way you can run bear
continuously during work, and it keeps the compilation database up to date. File deletion and
addition are both considered. But build process change (modifying compiler flags) will cause
duplicate entries.
-v, --verbose
Make bear more verbose.
-l library
Specify the preloaded library location. Default value provided. (This option mainly for
development purposes.)
-n Disable filter. The output is also a JSON formated file. But the result is not a compilation
database. It contains all available information of the exec calls. (This option mainly for
development purposes.)
OUTPUT
There are two version of output formats. One is defined by the clang tooling. This goes like this:
[
{ "directory": "/home/user/llvm/build",
"command": "clang++ -Irelative -c -o file.o file.cc",
"file": "file.cc" },
...
]
To achieve this bear has to run some filtering and formating. Build tools exec many commands during the
build process. Bear has to find was that a compiler call, and what was the source file? The other
output format is generated by the -n flag. (This output is not formalized, it's used to debug bear
itself.)
EXIT STATUS
Bear exit status is the exit status of the build command. Except when bear crashes, then it sets to non
zero.
ENVIRONMENT
BEAR_OUTPUT
The place of the temporary files where client shall report exec calls. Value set by bear,
overrides previous value for child processes.
LD_PRELOAD
Used by the dynamic loader on Linux, FreeBSD and other UNIX OS. Value set by bear, overrides
previous value for child processes.
DYLD_INSERT_LIBRARIES
Used by the dynamic loader on OS X. Value set by bear, overrides previous value for child
processes.
DYLD_FORCE_FLAT_NAMESPACE
Used by the dynamic loader on OS X. Value set by bear, overrides previous value for child
processes.
FILES
/usr/lib/x86_64-linux-gnu/bear/libear.so
bear library to implement exec calls.
SEE ALSO
ld.so(8), exec(3)
BUGS
Because Bear uses LD_PRELOAD or DYLD_INSERT_LIBRARIES environment variables, it does not append to it,
but overrides it. So builds which are using these variables might not work. (I don't know any build tool
which does that, but please let me know if you do.)
Security extension/modes on different operating systems might disable library preloads. This case Bear
behaves normaly, but the result compilation database will be empty. (Please make sure it's not the case
when reporting bugs.) Notable examples for enabled security modes are: SIP on OS X Captain and SELinux
on Fedora, CentOS, RHEL.
COPYRIGHT
Copyright (C) 2012-2016 by László Nagy <https://github.com/rizsotto/Bear>
AUTHORS
László Nagy.