Change Default Linux Shell

Needs sudo privileges: to change the default shell:

chsh

http://forums.devshed.com/unix-help-35/how-to-change-default-shell-52749.html

Simple Network Test Script

This is a simple script to log network outages on a local network

root@ubuntu:/mnt/root/usr/local/bin# more lifeline
#!/bin/bash

PING='/bin/ping'
EXTHOST1='www.google.com'
EXTHOST2='sun.iwu.edu'
INTHOST='192.168.1.1'
LOG='/var/log/network_outages'
WAITTIME=120

echo "NETWORK STATUS SCRIPT: Started " `date` >> $LOG
while [ 1=1 ]
do
   dater=`date +%Y.%m.%d-%H.%M.%S`
   $PING -q -c1 $EXTHOST1
   ret=$?
   echo "RET: $ret"
   if [ $ret -ne 0 ]
   then
     echo "EXTERNAL_PING(1): outage detected $dater" >> $LOG
   fi

   dater=`date +%Y.%m.%d-%H.%M.%S`
   $PING -q -c1 $EXTHOST2
   ret=$?
   echo "RET: $ret"
   if [ $ret -ne 0 ]
   then
     echo "EXTERNAL_PING(2): outage detected $dater" >> $LOG
   fi

   $PING -q -c1 $INTHOST
   ret=$?
   echo "RET: $ret"
   if [ $ret -ne 0 ]
   then
     echo "INTERNAL_PING: outage detected $dater" >> $LOG
   fi

   sleep $WAITTIME
done

Get File Extension in Shell Script

Returns the last file extension in the file name
echo "thisfile.txt.log"awk -F . '{print $NF}' # returns "log"

http://liquidat.wordpress.com/2007/09/29/short-tip-get-file-extension-in-shell-script/