Checking your Unix/Linux Filesystem for free space
I recently found two useful scripts on finding available disk space of your system. :-)

Script 1 from http://www.sun.com/bigadmin/scripts/submittedScripts/fscheck.ksh.txt
#! /usr/bin/ksh

###
### This script can be run from cron to periodically check
### filesystems for low disk space and send an e-mail.
###
### Variables:
### MAXSIZE = percentage filesystem must be full before notification
### NOTIFY = email address to notify when file system reaches MAXSIZE
###

### Configurable variables here
MAXSIZE=90
NOTIFY=you@yourcompany.com
HOSTNAME=`hostname`

# Add filesystems you wish to skip from checking
FSLIST=`df -k | grep -v "cdrom" | grep -v "mnt" | awk '{ fssize=substr($5,1,index($5,"%")-1)
if (int(fssize) > int(maxsize)) {
print $6":"fssize
}
}' maxsize=$MAXSIZE`

### Were there any fs to report?
if [ -z $FSLIST ]; then
echo "There were no reportable filesystems."
exit 0
fi

### Mail out the list if there is one
for fs in $FSLIST
do
FS=`echo $fs | cut -f1 -d:`
SIZE=`echo $fs | cut -f2 -d:`
MESSAGE="Subject: $HOSTNAME File System Alert: $FS at $SIZE %"
echo $MESSAGE | mail $NOTIFY
done

### Exit gracefully
exit 0


### This script is submitted to BigAdmin by a user of the BigAdmin community.
### Sun Microsystems, Inc. is not responsible for the
### contents or the code enclosed.
###
###
### Copyright 2006 Sun Microsystems, Inc. ALL RIGHTS RESERVED
### Use of this software is authorized pursuant to the
### terms of the license found at
### http://www.sun.com/bigadmin/common/berkeley_license.html

Script 2 from http://www.sun.com/bigadmin/scripts/submittedScripts/dfh.sh.txt
#!/bin/sh
#
# title: Displays the amount of disk space
# subtitle: Disk space mounted in MB or GB
# creation date: 11 november 2002
# modification date: 26 janvier 2006
# version: 1.0
# author: Fabbri Pascal @ ?pfL
# Swiss Federal Institute of Technology Lausanne
# email: pascal.fabbri@epfl.ch
# file name: $HOME/scripts/dfh
# description: Display the amount of disk space occupied by file systems
# in MB or in GB.
#

ECHO="/bin/echo"

if [ $# -gt 0 ] || [ $# -lt 2 ]
then
case $1 in
-g)
sizeIn='GB'
;;
-m)
sizeIn='MB'
;;
-h)
${ECHO} Usage: `basename $0` \[-m\|-g\]
${ECHO} "\t -m space in MegaByte (MB)"
${ECHO} "\t -g space in GigaByte (GB)"
exit 1
;;
*)
sizeIn='MB'
;;
esac
else
${ECHO} "Too many options !"
exit 1
fi

DF="/bin/df"
AWK="/usr/bin/awk"

if [ -r '/usr/bin/uname' ]
then
OSName=`/usr/bin/uname -s`
elif [ -r '/bin/uname' ]
then
OSName=`/bin/uname -s`
else
${ECHO} "uname command not found !"
exit 1
fi

AWK_FILE_GB='
BEGIN {
size=0
used=0
avail=0
getline;
printf "%-21s %6s %6s %6s %4s\n","","(gb)","(gb)","(gb)","(%)"
printf "%-21s %6s %6s %6s %4s %s\n","Filesystem","size","used","avail","used","Mounted on"
}
{
printf "%-21s %6.2f %6.2f %6.2f %4s %s\n",$1,$2/1024/1024,$3/1024/1024,$4/1024/1024,$5,$6
size+=$2
used+=$3
avail+=$4
}
END {
printf "%-21s %6s %6s %6s\n","","------","------","------"
printf "%-21s %6.2f %6.2f %6.2f\n", "",size/1024/1024,used/1024/1024,avail/1024/1024
}'

AWK_FILE_MB='
BEGIN {
size=0
used=0
avail=0
getline;
printf "%-21s %6s %6s %6s %4s\n", "","(mb)","(mb)","(mb)","(%)"
printf "%-21s %6s %6s %6s %4s %s\n", "Filesystem","size","used","avail","used","Mounted on"
}
{
printf "%-21s %6d %6d %6d %4s %s\n", $1,$2/1024,$3/1024,$4/1024,$5,$6
size+=$2
used+=$3
avail+=$4
}
END {
printf "%-21s %6s %6s %6s\n", "","------","------","------"
printf "%-21s %6d %6d %6d\n", "",size/1024,used/1024,avail/1024
}'

case $sizeIn in
GB)
AWK_FILE=${AWK_FILE_GB}
;;
MB)
AWK_FILE=${AWK_FILE_MB}
;;
*)
${ECHO} "Do nothing !"
;;
esac

case ${OSName} in
SunOS)
(${DF} -kF ufs; ${DF} -kF zfs | ${AWK} 'BEGIN{getline} {print}') | ${AWK} "${AWK_FILE}"
;;
FreeBSD)
${DF} -kt ufs | ${AWK} "${AWK_FILE}"
;;
Darwin)
${DF} -kt hfs,ufs,msdos | ${AWK} "${AWK_FILE}"
;;
Linux)
${DF} -k | ${AWK} "${AWK_FILE}"
;;
*)
$ECHO Error: Unknown Operating System!
esac


### This script is submitted to BigAdmin by a user of the BigAdmin community.
### Sun Microsystems, Inc. is not responsible for the
### contents or the code enclosed.
###
###
### Copyright 2006 Sun Microsystems, Inc. ALL RIGHTS RESERVED
### Use of this software is authorized pursuant to the
### terms of the license found at
### http://www.sun.com/bigadmin/common/berkeley_license.html