You may find that /tmp becomes full regularly. This is usually the result of user's php scripts that aren't removing files they create in /tmp. There is a third-party program for clearing the /tmp directory called tmpwatch. This article will show you how to install tmpwatch and set up a cron job so that it can clean the /tmp directory of old files on a regular basis.
1. Install tmpwatch if it's not installed. If you run this command when tmpwatch is already installed and on the latest version, it will tell you there is nothing to do and no harm will be caused.
yum install tmpwatch
2. Run tmpwatch to clear the /tmp partition of files over a week old now:
tmpwatch --mtime --all 168 /tmp
Check to see if some files were actually removed from /tmp. If not, decrease the number of hours (in this case 168) until enough files are removed to give sufficient space in /tmp. Do not lower the number below 12.
3. Add tmpwatch to root's crontab to clear old files (more than a week old) every night. If you needed to lower the number of hours in step 2, lower it here as well.
echo "0 0 * * * tmpwatch -mtime --all 168 /tmp" >> /var/spool/cron/root
4. Reload the crontab so that the new job takes action.