How to Create or Edit a crontab File

Before You Begin

If you are creating or editing a crontab file that belongs to root or another user you must become root.

You do not need to become root to edit your own crontab file.

1. Create a new crontab file, or edit an existing file.

   # crontab -e [username]

   where username specifies the name of the user’s account for which you want to create or edit a crontab file. You can create your own crontab file without superuser privileges, but you must have superuser privileges to creating or edit a crontab file for root or another user.

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   Caution – If you accidentally type the crontab command with no option, press the interrupt character for your editor. This character allows you to quit without saving changes. If you instead saved changes and exited the file, the existing crontab file would be overwritten with an empty file.

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2. Add command lines to the crontab file.Follow the syntax described in Syntax of crontab File Entries. The crontab file will be placed in the /var/spool/cron/crontabs directory.
3. Verify your crontab file changes.

   # crontab -l [username]

Example 14-1 Creating a crontab File

The following example shows how to create a crontab file for another user.

# crontab -e jones

The following command entry added to a new crontab file automatically removes any log files from the user’s home directory at 1:00 a.m. every Sunday morning. Because the command entry does not redirect output, redirect characters are added to the command line after *.log. Doing so ensures that the command executes properly.

# This command helps clean up user accounts.
1 0 * * 0 rm /home/jones/*.log > /dev/null 2>&1

How to Verify That a crontab File Exists

To verify that a crontab file exists for a user, use the ls -l command in the /var/spool/cron/crontabs directory. For example, the following output shows that crontab files exist for users jones and smith.

$ ls -l /var/spool/cron/crontabs