The Complete Beginner's Guide to Linux

Linux.com ^ | 13 August 2014 | Jack Wallen

[zeugma]

Nice sed!

Here's a fun trick for linuxers....

#!/usr/bin/bash

if [ "$1" == "" -o "$2" == "" ]
    then
      echo "Syntax:"
      echo "$0 extension path"
    exit
fi

ls -lR $2 | grep \\.$1 | awk '{ total += $5 } END { print total }'

What does it do? It accepts one arguments. The first  argument is a file extension. The second is a directory name. If you want it to start from the directory you are in, use ".".

This script will start in the directory specified and will find all files with that extension, add up all the file sizes, then print a total for that file type.

$ columnsum mp3 /home/av/music/bluegrass/
1500935414
$ columnsum mp3 .
488423164

 

[ShadowAce]

Pretty cool. Are you a fan of CommandlineFu?

[zeugma]

Pretty cool. Are you a fan of CommandlineFu?

Yeah, it's been a while since I've been to that site, but I recall it having some really cool one liners.

I actually used that very simple script to teach some of the basics of life in the shell to a nephew. It was originally exactly 1 line that was hardcoded to look for and total up mp3 files. We first made it look for any type of file extension, which is actually trickier than you'd think because you have to escape the "." or you'll get false positives. Then we made it take a path for input. Lastly, put some checking to make sure you had two arguments. Was kinda cool. Very simple, but he was easily able to understand it. The idea I was trying to show was how to take something that did one thing and make it more general.