stderred
stderr in red.
About
stderred hooks on write() and a family of stream functions (fwrite, fprintf,
error...) from libc in order to colorize all stderr output that goes to
terminal thus making it distinguishable from stdout. Basically it wraps text
that goes to file with descriptor "2" with proper ANSI escape codes making text
red.
It's implemented as a shared library and doesn't require recompilation of
existing binaries thanks to preload/insert feature of dynamic linkers.
It's supported on Linux (with LD_PRELOAD), FreeBSD (also LD_PRELOAD) and
OSX (with DYLD_INSERT_LIBRARIES).
Watch this intro asciicast to see it in action.
Installation
Clone this repository:
$ git clone git://github.com/sickill/stderred.git
$ cd stderred
Important: In all cases below make sure that path to libstderred.so is absolute!
Linux and FreeBSD
Make sure you have cmake and the gcc toolchain required for compilation installed:
# Ubuntu
sudo apt-get install build-essential cmake
# Fedora
sudo yum install make cmake gcc gcc-c++
# FreeBSD
pkg install cmake
Build:
$ make
Export LD_PRELOAD variable in your shell's config file by putting following
in your .bashrc/.zshrc:
export LD_PRELOAD="/absolute/path/to/stderred/build/libstderred.so${LD_PRELOAD:+:$LD_PRELOAD}"
Multi-arch Linux and FreeBSD
On some Linux distros you can install 32-bit packages on 64-bit system. Shared
libraries compiled for 64-bit doesn't work with 32-bit binaries though. It
happens that 64-bit binaries call 32-bit ones resulting in warning message
printed to terminal about not compatible LD_PRELOAD shared lib.
Fortunately Linux's dynamic linker has a feature called Dynamic String Token
(DST). It allows dynamic substitution of $LIB token in LD_PRELOAD variable
with "lib" or "lib64" respectively for 32 and 64-bit binaries when the binary
is being run. Thanks to that you can compile stderred for both architectures
and automatically use proper version of this shared library.
On 64-bit Fedora, for example, you need to install libc development headers for
both architectures:
$ sudo yum install glibc-devel.i686 glibc-devel.x86_64
compile it like this:
$ make 32 && make 64
and export LD_PRELOAD like this in your shell's config:
export LD_PRELOAD="/path/to/stderred/\$LIB/libstderred.so${LD_PRELOAD:+:$LD_PRELOAD}"
* Note that there is no support for $LIB token on Ubuntu.
OSX
$ make
Export DYLD_INSERT_LIBRARIES variable in your shell's config file by putting following
in your .bashrc/.zshrc:
export DYLD_INSERT_LIBRARIES="/absolute/path/to/build/libstderred.dylib${DYLD_INSERT_LIBRARIES:+:$DYLD_INSERT_LIBRARIES}"
Universal lib on OSX
OSX solves multi-arch problem (described above in "Multi-arch Linux and
FreeBSD") by supporting so called "universal" libraries that include 2 copies
of code compiled for both 32 and 64-bit architecture in the single library
file.
If you feel you will want universal library then build it this way:
$ make universal
and export shell env like above.
Checking if it works
$ find -q
$ cat nonexistingfile
$ ls nonexistingfile
$ python -c 'import os; print "Yo!"; os.write(2, "Jola\n\r")'
$ STDERRED_ESC_CODE=$(echo -e '\e[;92m') ruby -e 'puts "Yo!"; warn "Jola"'
"Jola" should be printed in red color.
Alternative way: aliasing
Alternative to enabling it globally via shell config is to create alias and
use it to selectively colorize stderr for the commands you run:
$ alias stderred="LD_PRELOAD=/absolute/path/to/build/libstderred.so\${LD_PRELOAD:+:\$LD_PRELOAD}"
$ stderred java lol
Configuration
Custom color code
If you prefer other color or you want to use additional escape codes
(for bold/bright, italic, different background) you can export
STDERRED_ESC_CODE with desired escape code sequence.
Here's an example for bold red:
bold=$(tput bold, tput md)
red=$(tput setaf 1)
export STDERRED_ESC_CODE=`echo -e "$bold$red"`
Program Blacklisting
Some programs abuse stderr and print stuff on it even when they really
shouldn't. If you want to turn off stderred for particular programs you can
export STDERRED_BLACKLIST with a desired POSIX Extended Regular Expression
matching names of these programs.
Here's an example that will blacklist bash, and all programs with names
starting with "test":
export STDERRED_BLACKLIST="^(bash, test.*)$"
Alternative implementations
Simpler and much less reliable solution when using Zsh is to use named pipes
trick proposed on
the archived Gentoo Linux wiki.
It has some race condition/buffering issues and breaks on interactive commands
writing to stderr though.
Authors
Current implementation:
Original concept and
initial implementation:
- Asheesh Laroia
License
You are free to use this program under the terms of the license found in
LICENSE file.