You were completely right, I'm fixing the code in GitHub, thanks!
$this->bbcode_second_pass_quote('smcd', 'H')ey,
I enjoy your script, thanks

I think there is a logic issue though, the conditionals are OR and should be AND. For example, set PERCENT = 71 (my current disk usage) and it drops out saying:
[root@goflex ~]# /opt/gauges_right.sh sda1
percent 71
Your using an amount of disk space that is less or equal to 50%
Changing the -o to -a:
[root@goflex ~]# /opt/gauges_right.sh sda1
percent 71
Your using an amount of disk space that is less or equal to 75%