4 coloredstderr is a small library which uses 'LD_PRELOAD' to color stderr.
7 Like all solutions using 'LD_PRELOAD' it only works with dynamically linked
8 binaries. Statically linked binaries, for example valgrind, are not supported.
9 setuid binaries are also not supported ('LD_PRELOAD' disabled for security
13 It was inspired by stderred [2]. Similar solutions (using 'LD_PRELOAD')
16 - stderred [1], but doesn't `follow' dups (I somehow missed it when looking
17 for existing implementations)
18 - stderred [2], but only hooks `write()`
20 [1]: https://github.com/sickill/stderred
21 [2]: https://github.com/trapd00r/stderred
23 Most other existing solutions use a second process which colors its input and
24 pipe stderr to it. However this creates different runtime behaviour resulting
25 in a different ordering of the output. Partial lines (no newline) also often
32 - C99 compiler (variable length arrays)
33 - dynamic linker/loader which supports 'LD_PRELOAD' (e.g. GNU/Linux's ld.so)
39 ./configure && make && make check
41 Then either install the library with `make install` or just copy it from
42 `src/.libs/` to wherever you want to install it:
44 rm -f /destination/path/for/library/libcoloredstderr.so
45 cp -L src/.libs/libcoloredstderr.so /destination/path/for/library/
47 *Important:* If you install `libcoloredstderr.so` manually, make sure _not_ to
48 use plain `cp` to overwrite an existing `libcoloredstderr.so` file which is in
49 use! Doing so will crash all processes which were started with 'LD_PRELOAD'
50 set to this file. This is not a bug in coloredstderr, but a general problem.
51 `cp` truncates the file which causes the `mmap()` ed library to be in an
52 inconsistent state causing a segmentation fault when using any functions of
53 the library. Just remove the file first and then copy it. `make install`
54 handles the install in this way and is therefore not affected.
56 As a simple safeguard, `make` builds and installs the `libcoloredstderr.so`
57 file non-writable to prevent accidental overwrites. Even if the overwrite is
58 forced with `cp -f`, the file is unlinked and recreated by `cp` because the
59 file is non-writable, preventing the problem.
65 Set 'LD_PRELOAD' to include the _absolute_ path to `libcoloredstderr.so`:
67 LD_PRELOAD=/absolute/path/to/libcoloredstderr.so
69 The 'COLORED_STDERR_FDS' environment variable must be set to the file
70 descriptors which should be colored (comma separated list). Normally this is
75 The trailing comma is important!
78 A default setup could look like this:
80 LD_PRELOAD="$HOME/bin/libcoloredstderr.so"
82 export LD_PRELOAD COLORED_STDERR_FDS
85 The following additional environment variables are available:
87 - 'COLORED_STDERR_PRE'
88 String to write before each write to stderr, defaults to "\033[91m" (bright
90 - 'COLORED_STDERR_POST'
91 String to write after each write to stderr, defaults to "\033[0m" (reset
93 - 'COLORED_STDERR_FORCE_WRITE'
94 If set to an non-empty value add pre/post strings even when not writing to a
95 terminal, e.g. when writing to a file. By default, only writes to a terminal
99 To set custom colors as pre/post strings you can use the `$''` feature of Bash
102 export COLORED_STDERR_PRE=$'\033[91m' # bright red
103 export COLORED_STDERR_POST=$'\033[0m' # default
105 Or to be more compatible you can use the following which should work in any
109 COLORED_STDERR_PRE="${esc}[91m" # red
110 COLORED_STDERR_POST="${esc}[0m" # default
111 export COLORED_STDERR_PRE COLORED_STDERR_POST
117 To enable debug mode, configure coloredstderr with '--enable-debug'.
119 *Important:* Debug mode enables `assert()`s in the code which might abort the
120 process if an error condition is detected!
122 Debug mode is slower than normal mode. To log only warnings without the
123 overhead of debug mode use '--enable-warnings'. `assert()`s are not enabled
124 with '--enable-warnings', so it's safe to use.
126 Debug messages are written to the file `colored_stderr_debug_log.txt` in the
127 current working directory _if_ it exists. If it exists debug messages are
128 appended. Be careful, this file might grow very quickly.
130 *Important:* Warnings are written to `$HOME/colored_stderr_warning_log.txt`
131 even if it _does not_ exist (only if debug or warning mode is enabled)! If it
132 doesn't exist it's created. An existing file isn't overwritten, but the
133 warnings are appended at the end.
139 If you find any bugs not mentioned in this document please report them to
140 <simon@ruderich.org> with coloredstderr in the subject.
146 Written by Simon Ruderich <simon@ruderich.org>.
152 coloredstderr is licensed under GPL version 3 or later.
154 Copyright (C) 2013 Simon Ruderich
156 This program is free software: you can redistribute it and/or modify
157 it under the terms of the GNU General Public License as published by
158 the Free Software Foundation, either version 3 of the License, or
159 (at your option) any later version.
161 This program is distributed in the hope that it will be useful,
162 but WITHOUT ANY WARRANTY; without even the implied warranty of
163 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
164 GNU General Public License for more details.
166 You should have received a copy of the GNU General Public License
167 along with this program. If not, see <http://www.gnu.org/licenses/>.