How-to clean your /tmp directory with tmpwatch

Question

How do you clean your /tmp directory with tmpwatch?

Answer

1. Install tmpwatch (if it's not already installed) by running the following command:

   # yum install tmpwatch

2. Check how many files are in /tmp:

   # ls -1 /tmp | wc -l

3. Run tmpwatch to clear the /tmp partition of files over a week old now. This command ignores symlinks and preserves certain systemd data stored in /tmp:

   # tmpwatch --verbose --mtime -l -X "/tmp/systemd-private*" 168 /tmp

4. 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.  

   Warning: Do not lower the number below 12. 

   # ls -1 /tmp | wc -l

5. Open the root crontab:

   # crontab -e

6. Add tmpwatch to root's crontab to clear old files (more than a week old) every night.  If you lowered the number of hours in step 3, lower it here as well.

   CONFIG_TEXT: 0 0 * * * tmpwatch --mtime -l -X "/tmp/systemd-private*" 168 /tmp

Additional Resources

How to edit the root crontab