Shell, Horizontal grep
grep is very helpull filtering lines, but how to easily
filter tokens in lines?
First answer is use cut or awk if things get hairy. But
as I spend 99% of my time on command line I do really like
small commands that to smart things. This gives me productivity.
This is a small perl oneliner wrapped in a shell function that
can filter tokens in lines. Think it as an horizontal grep.
It iterates over tokens in a line and print the ones that matches.
hgrep() { perl -nase 'foreach(@F){print $_, "\n" if /$p/}' -- -p=$1; }
I use it, usually, after grep to take desired tokens. So, imagine that you
need to take the current working directory a process is using. You can get this
from the PWD environment. Imagine that the pid of the process is 1234. You
may know that e flag of top brings the environment of it. But all variables
at spread at same line. You can use the above funtion to filter it easily.
ps ewww -p 1234 | hgrep PWD
PWD=/
OLDPWD=/root
I hope that this help you as helped me! Cheers!