README ====== coloredstderr is a small library which uses 'LD_PRELOAD' to color stderr. Like all solutions using 'LD_PRELOAD' it only works with dynamically linked binaries. Statically linked binaries, for example valgrind, are not supported. It was inspired by stderred [2]. Similar solutions (using 'LD_PRELOAD') include: - stderred [1], but doesn't `follow' dups (I somehow missed it when looking for existing implementations) - stderred [2], but only hooks `write()` [1]: https://github.com/sickill/stderred [2]: https://github.com/trapd00r/stderred Most other existing solutions use a second process which colors its input and pipe stderr to it. However this creates different runtime behaviour resulting in a different ordering of the output. Partial lines (no newline) also often cause problems. DEPENDENCIES ------------ - C99 compiler (variable length arrays) - dynamic linker/loader which supports 'LD_PRELOAD' (e.g. GNU/Linux's ld.so) USAGE ----- Set 'LD_PRELOAD' to include the _absolute_ path to `libcoloredstderr.so`: LD_PRELOAD=/absolute/path/to/libcoloredstderr.so The 'COLORED_STDERR_FDS' environment variable must be set to the file descriptors which should be colored (comma separated list). Normally this is just 2 (stderr): COLORED_STDERR_FDS=2, The trailing comma is important! A default setup could look like this: LD_PRELOAD="$HOME/bin/libcoloredstderr.so" COLORED_STDERR_FDS=2, export LD_PRELOAD COLORED_STDERR_FDS The following additional environment variables are available: - 'COLORED_STDERR_PRE' String to write before each write to stderr, defaults to "\033[91m" (bright red). - 'COLORED_STDERR_POST' String to write after each write to stderr, defaults to "\033[0m" (reset color). - 'COLORED_STDERR_FORCE_WRITE' If set to an non-empty value add pre/post strings even when not writing to a terminal, e.g. when writing to a file. By default, only writes to a terminal are colored. DEBUG ----- To enable debug mode, configure coloredstderr with '--enable-debug'. *Important:* Debug mode enables `assert()`s in the code which might abort the process if an error condition is detected! Debug mode is slower than normal mode. To log only warnings without the overhead of debug mode use '--enable-warnings'. `assert()`s are not enabled with '--enable-warnings', so it's safe to use. Debug messages are written to the file `colored_stderr_debug_log.txt` in the current working directory _if_ it exists. If it exists debug messages are appended. Be careful, this file might grow very quickly. *Important:* Warnings are written to `$HOME/colored_stderr_warning_log.txt` even if it _does not_ exist (only if debug or warning mode is enabled)! If it doesn't exist it's created. An existing file isn't overwritten, but the warnings are appended at the end. BUGS ---- If you find any bugs not mentioned in this document please report them to with coloredstderr in the subject. AUTHORS ------- Written by Simon Ruderich . LICENSE ------- coloredstderr is licensed under GPL version 3 or later. Copyright (C) 2013 Simon Ruderich This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see .