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.
11 It was inspired by stderred [2]. Similar solutions (using 'LD_PRELOAD')
14 - stderred [1], but doesn't `follow' dups (I somehow missed it when looking
15 for existing implementations)
16 - stderred [2], but only hooks `write()`
18 [1]: https://github.com/sickill/stderred
19 [2]: https://github.com/trapd00r/stderred
21 Most other existing solutions use a second process which colors its input and
22 pipe stderr to it. However this creates different runtime behaviour resulting
23 in a different ordering of the output. Partial lines (no newline) also often
30 - C99 compiler (variable length arrays)
31 - dynamic linker/loader which supports 'LD_PRELOAD' (e.g. GNU/Linux's ld.so)
37 ./configure && make && make check
39 Then either install the library with `make install` or just copy it from
40 `src/.libs/` to wherever you want to install it:
42 rm -f /destination/path/for/library/libcoloredstderr.so
43 cp -L src/.libs/libcoloredstderr.so /destination/path/for/library/
45 *Important:* If you install `libcoloredstderr.so` manually, make sure _not_ to
46 use plain `cp` to overwrite an existing `libcoloredstderr.so` file which is in
47 use! Doing so will crash all processes which were started with 'LD_PRELOAD'
48 set to this file. This is not a bug in coloredstderr, but a general problem.
49 `cp` truncates the file which causes the `mmap()` ed library to be in an
50 inconsistent state causing a segmentation fault when using any functions of
51 the library. Just remove the file first and then copy it. `make install`
52 handles the install in this way and is therefore not affected.
58 Set 'LD_PRELOAD' to include the _absolute_ path to `libcoloredstderr.so`:
60 LD_PRELOAD=/absolute/path/to/libcoloredstderr.so
62 The 'COLORED_STDERR_FDS' environment variable must be set to the file
63 descriptors which should be colored (comma separated list). Normally this is
68 The trailing comma is important!
71 A default setup could look like this:
73 LD_PRELOAD="$HOME/bin/libcoloredstderr.so"
75 export LD_PRELOAD COLORED_STDERR_FDS
78 The following additional environment variables are available:
80 - 'COLORED_STDERR_PRE'
81 String to write before each write to stderr, defaults to "\033[91m" (bright
83 - 'COLORED_STDERR_POST'
84 String to write after each write to stderr, defaults to "\033[0m" (reset
86 - 'COLORED_STDERR_FORCE_WRITE'
87 If set to an non-empty value add pre/post strings even when not writing to a
88 terminal, e.g. when writing to a file. By default, only writes to a terminal
92 To set custom colors as pre/post strings you can use the `$''` feature of Bash
95 export COLORED_STDERR_PRE=$'\033[91m' # bright red
96 export COLORED_STDERR_POST=$'\033[0m' # default
98 Or to be more compatible you can use the following which should work in any
102 COLORED_STDERR_PRE="${esc}[91m" # red
103 COLORED_STDERR_POST="${esc}[0m" # default
104 export COLORED_STDERR_PRE COLORED_STDERR_POST
110 To enable debug mode, configure coloredstderr with '--enable-debug'.
112 *Important:* Debug mode enables `assert()`s in the code which might abort the
113 process if an error condition is detected!
115 Debug mode is slower than normal mode. To log only warnings without the
116 overhead of debug mode use '--enable-warnings'. `assert()`s are not enabled
117 with '--enable-warnings', so it's safe to use.
119 Debug messages are written to the file `colored_stderr_debug_log.txt` in the
120 current working directory _if_ it exists. If it exists debug messages are
121 appended. Be careful, this file might grow very quickly.
123 *Important:* Warnings are written to `$HOME/colored_stderr_warning_log.txt`
124 even if it _does not_ exist (only if debug or warning mode is enabled)! If it
125 doesn't exist it's created. An existing file isn't overwritten, but the
126 warnings are appended at the end.
132 If you find any bugs not mentioned in this document please report them to
133 <simon@ruderich.org> with coloredstderr in the subject.
139 Written by Simon Ruderich <simon@ruderich.org>.
145 coloredstderr is licensed under GPL version 3 or later.
147 Copyright (C) 2013 Simon Ruderich
149 This program is free software: you can redistribute it and/or modify
150 it under the terms of the GNU General Public License as published by
151 the Free Software Foundation, either version 3 of the License, or
152 (at your option) any later version.
154 This program is distributed in the hope that it will be useful,
155 but WITHOUT ANY WARRANTY; without even the implied warranty of
156 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
157 GNU General Public License for more details.
159 You should have received a copy of the GNU General Public License
160 along with this program. If not, see <http://www.gnu.org/licenses/>.