The simplest way to create a crontab file is to use the crontab -e command. This command invokes the text editor that has been set for your system environment. The default editor for your system environment is defined in the EDITOR environment variable. If this variable has not been set, the crontab command uses the default editor, ed. Preferably, you should choose an editor that you know well.
$ which $EDITOR $ $ EDITOR=vi $ export EDITOR
When you create a crontab file, it is automatically placed in the /var/spool/cron/crontabs directory and is given your user name. You can create or edit a crontab file for another user, or root, if you have superuser privileges.
If you are creating or editing a crontab file that belongs to root or another user you must become superuser or assume an equivalent role. Roles contain authorizations and privileged commands. For more information about roles, see Configuring RBAC (Task Map) in System Administration Guide: Security Services.
You do not need to become superuser to edit your own crontabfile.
$ 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.
Follow the syntax described in Syntax of crontab File Entries. The crontab file will be placed in the /var/spool/cron/crontabs directory.
# crontab -l [username]
Example 8-1 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
$ ls -l /var/spool/cron/crontabs -rw-r--r-- 1 root sys 190 Feb 26 16:23 adm -rw------- 1 root staff 225 Mar 1 9:19 jones -rw-r--r-- 1 root root 1063 Feb 26 16:23 lp -rw-r--r-- 1 root sys 441 Feb 26 16:25 root -rw------- 1 root staff 60 Mar 1 9:15 smith -rw-r--r-- 1 root sys 308 Feb 26 16:23 sys
Verify the contents of user's crontab file by using the crontab -l command as described in How to Display a crontab File.