Shell tips: Finally colorized stderr, stdout!

John, Cool and helpful idea

Hi John -- interesting use of process substition there. Here's what I think: A much more portable way to introduce color is to use the tput utility to get the color-strings for the environment dynamically -- I often use the following in my scripts: # # Use the tput(1) command to obtain color-codes for the current terminal # declare -x tputReset=$(tput sgr0) declare -x tputRed=$(tput setaf 1) # ERROR-level messages declare -x tputBold=$(tput bold) declare -x tputYellow=$(tput setaf 3) # WARNING-level messages declare -x tputGreen=$(tput setaf 2) Then, instead of your line: echo -e "$RED$line$RESET" I go with: echo -e "${tputRed}$line${tputReset}" BUT, and this is a big "BUT" for me, using your idea to make the stderr messages show up in red by invoking commands like: # ls aNonExistentFile aFileThatDoesExist 2> >(colorize) Does not work so well because they often out in wrong order, which can be confusing in more realistic examples. That is becuase of line buffering by the redirection of stderr to your colorize process. Basically, according to what I have been able to understand on this (only minimal research), the shell (or something else) will NOT buffer lines when they are to the normal stdout and stderr, but, as soon as you redirect, something changes there and the output is buffered (as per standard UNIX I/O bufferinf), which causes the stdout and stderr messages to end up in the wrong order (though it does seem a bit random at times). What is interesting is that your example does not reveal this, and, to be honest, using your method, where the color codes are "hard-coded" as 'RED="\033[0;31m" '; the order did seem to be more correct, but not always. BTW: all my 20 minutes of testing was on OS X 10.11.6 ( kerel release 15.6.0 ) and BASH 4.3.42. I just haven't tried in under Linux nor Solaris yet (sorry). Anyway, thanks for that very interesting way to redirect stderr to a process -- that I did not know, though I use the other form, ' < <(someProcess)', all the time in my while loops, etc... All the best good buddy, Kevin

Cool idea. Thanks for sharing. Your script didn't work for me out of the gate (stupid OS/X). Here is my version: #!/bin/bash #colorize by JohnnyB - boeroboy@gmail.com RED="\033[0;31m" RESET="\033[0m" while read line do echo -e "$RED$line$RESET" done < "${1:-/dev/stdin}" But then I thought it could be a touch simpler with perl #!/usr/bin/env perl #colorize by JohnnyB - boeroboy@gmail.com $e=chr(27); while (<>) { print "${e}[0;31m$_${e}[0m"; }

First time in a long while I've seen some actual job related content on this so-called "professional" networking platform. Nice one John!