Funner

Parsing Free space Output

Here’s a really short regex that can be used to parse free space output and verify each mounted disk has at least 89% free space. This comes in handy if you do any of your own systems monitoring that include *nix boxes.

So let’s say you have this output from various machines:

db:
Filesystem            Size  Used Avail Use% Mounted on
47G  3.1G   41G   7% /
/dev/sda1              99M   16M   79M  17% /boot
tmpfs                 1.5G     0  1.5G   0% /dev/shm

www:
Filesystem            Size  Used Avail Use% Mounted on
76G   16G   56G  22% /
/dev/sda1              99M   17M   78M  18% /boot
tmpfs                 1.5G     0  1.5G   0% /dev/shm

email:
Filesystem            Size  Used Avail Use% Mounted on
/dev/sda2              13G  4.1G  9.0G  32% /
udev                  1.9G  116K  1.9G   1% /dev
/dev/sdb1             241G   15G  214G   7% /var/data
/dev/sdc1             241G   15G  214G   7% /var/backup

This regex will do the trick:

/([9]).%/

It can be integrated into a Ruby statement as follows:

IO.popen(“cat /path/to/freespace_output 2>&1”) do |f|
while line = f.gets do
lowdisk_systems += 1 if line =~ /([9]).%/i
end
end

In this case, lowdisk_systems gets incremented for each line of “/path/to/freespace_output” that is 90% or greater.

This example by itself is extremely limited in scope, but if integrated properly it can be useful.