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https://github.com/ku1ik/stderred

stderr in red
https://github.com/ku1ik/stderred

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stderr in red

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README 

        
# 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](https://asciinema.org/a/1705) to see it in action.



## Installation



Clone this repository:



    $ git clone git://github.com/ku1ik/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](http://comments.gmane.org/gmane.comp.lib.glibc.user/974)._



### 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.*)$"



## Authors



Current implementation:



* [Marcin Kulik](https://github.com/ku1ik/)

* [Chris Hoffman](https://github.com/cehoffman/)

* [Brian Tarricone](https://github.com/kelnos/)



[Original concept](http://www.asheesh.org/note/software/stderred.html) and

[initial implementation](http://git.asheesh.org/?p=zzz/colorize-stderr.git;a=summary):



* Asheesh Laroia



## License



You are free to use this program under the terms of the license found in

LICENSE file.