6.4.3.3. ...loading the crontab from a file?

When executed without any arguments, the crontab command will read the crontab configuration from the standard input. You can use this feature to load the configuration from a file:

$ crontab < /tmp/newcrontab

To see the current crontab configuration, use the -l option:

$ crontab -l

# Backup ~chris/oreilly/ to bluesky:~chris/backup/ as a tar archive

30 0,12 * * * /usr/local/bin/bluesky-backup-oreilly

# Update the local rawhide repository

0 5 * * * /usr/local/bin/rawhide-rsync

Putting these features together, you can create a simple script to edit a crontab configuration:

#!/bin/bash

# addtmpclean :: add a crontab entry to clean ~/tmp daily

(crontab -l ; echo "30 4 * * * rm -f ~/tmp/*")|crontab