Normally our server disk space will be increase at the same time we are not monitoring periodically, we know what will happen if the disk space is full. So create a shell script and send alert to you.

Create a shell file and give execute permission,

# cd /root

# vim

# chmod +x

copy the following line to shell file,

df -HlP | grep -vE '^Filesystem|tmpfs|cdrom' | awk '{ print $5 " " $1 }' | while read output;
      echo $output
      usep=$(echo $output | awk '{ print $1}' | cut -d'%' -f1 )
      partition=$(echo $output | awk '{ print $2 }' )
        if [ $usep -ge 95 ]; then
        echo "Running out of space \"$partition ($usep%)\" on $(hostname) as on $(date)" |
        mail -s "Alert: Almost out of disk space $usep%"

Set Cronjob:

Set cronjob on everyday for example morning 1.00 AM, Edit a cronjob file and add a line,
# crontab  -e

00 1 * * * /bin/sh /root/

Finally, restart cron service,
# /etc/init.d/crond restart