Mail somebody about space running low in some path (ksh, bash):

PATHS="/export/home /home"
AWK=/usr/bin/awk
DU="/usr/bin/du -ks"
GREP=/usr/bin/grep
DF="/usr/bin/df -k"
TR=/usr/bin/tr
SED=/usr/bin/sed
CAT=/usr/bin/cat
MAILFILE=/tmp/mailviews$$
MAILER=/bin/mailx
mailto="all@company.com"
for path in $PATHS
do
DISK_AVAIL=`$DF $path | $GREP -v "Filesystem" | $AWK '{print $5}'|$SED 's/%//g'`
if [ $DISK_AVAIL -gt 90 ];then
echo "Please clean up your stuff\n\n" > $MAILFILE
$CAT $MAILFILE | $MAILER -s "Clean up stuff" $mailto
fi
done

To find out the number of files of each type in your current directory

find ${*-.} -type f | xargs file | awk -F, '{print $1}' | awk '{$1=NULL;print $0}' | sort | uniq -c | sort -nr

One liner to find biggest file or directory.

du -sk ./* | sort -n | awk 'BEGIN{ pref[1]="K"; pref[2]="M"; pref[3]="G";} { total = total + $1; x = $1; y = 1; while( x > 1024 ) { x = (x + 1023)/1024; y++; } printf("%g%s\t%s\n",int(x*10)/10,pref[y],$2); } END { y = 1; while( total > 1024 ) { total = (total + 1023)/1024; y++; } printf("Total: %g%s\n",int(total*10)/10,pref[y]); }'