The crontab usage is:
Copy mode. Replace the crontab of the user who invoked the command with the content of file.
The -u is allowed only for super-user. With this option, the crontab of the user name is replaced.
List (-l), edit (-e) or remove (-r) the user’s crontab.
The -u is allowed only for super-user. With this option, the command operates on the crontab of the user name.
List (-l), edit (-e) or remove (-r) the crontab file in the crongroup of the current user (or user name). (see User Group Crontabs)
The -u option is allowed for super-user and any user whose primary group matches that of the user name.
The following table summarizes command line options of the
Operate on user cron group files.
Print a short command line usage summary and exit.
Interactively ask before removing or replacing.
List crontab content. When used with the -g option, this option lists the content of the crontab file in the group. If file is not supplied, displays the list of available crontabs in the group, along with their owners.
Remove the crontab.
Operate on crontab of user name.
Print program version, licensing information and exit.