Displaying crontab Files
The crontab -l command displays the contents of your crontab file much the way the cat command displays the contents of other types of files. You do not have to change directories to /var/spool/cron/crontabs (where crontab files are located) to use this command.
By default, the crontab -l command displays your own crontab file. To display crontab files that belong to other users, you must be superuser.
How to Display a crontab File
(Optional) Become superuser to display a crontab file that belongs to root or another user.
Display the crontab file.
$ crontab -l [username]
Where username specifies the name of the user's account for which you want to create or edit a crontab file. To create or edit crontab files requires superuser privileges.
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 is overwritten
with an empty file.
Example--Displaying a crontab File
The following example shows how to use the crontab -l command to display the contents of the user's default crontab file, the default root crontab file, and the crontab file belonging to another user.
$ crontab -l 13 13 * * * chmod g+w /home1/documents/*.book > /dev/null 2>&1 $ suPassword: # crontab -l #ident "@(#)root 1.19 98/07/06 SMI" /* SVr4.0 1.1.3.1 */ # # The root crontab should be used to perform accounting data collection. # # The rtc command is run to adjust the real time clock if and when # daylight savings time changes. # 10 3 * * * /usr/sbin/logadm 15 3 * * 0 /usr/lib/fs/nfs/nfsfind 1 2 * * * [ -x /usr/sbin/rtc ] && /usr/sbin/rtc -c > /dev/null 2>&1 30 3 * * * [ -x /usr/lib/gss/gsscred_clean ] && /usr/lib/gss/gsscred_clean # crontab -l jones 13 13 * * * cp /home/jones/work_files /usr/backup/. > /dev/null 2>&1 |
Removing crontab Files
By default, crontab file protections are set up so that you cannot inadvertently delete a crontab file by using the rm command. Instead, use the crontab -r command to remove crontab files.
By default, crontab -r removes your own crontab file. You must be superuser to remove crontab files that belong to superuser or other users.
You do not have to change directories to /var/spool/cron/crontabs (where crontab files are located) to use this command.
How to Remove a crontab File
(Optional) Become superuser to remove a crontab file that belongs to root or another user.
Remove the crontab file.
$ crontab -r [username]
Where username specifies the name of the user's account for which you want to create or edit a crontab file. To create or edit crontab files requires superuser privileges.
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 is overwritten
with an empty file.Verify that the crontab file is removed.
# ls /var/spool/cron/crontabs
Example--Removing a crontab File
The following example shows how user smith uses the crontab -r command to remove his crontab file.
$ ls /var/spool/cron/crontabs adm jones lp root smith sys uucp $ crontab -r $ ls /var/spool/cron/crontabs adm jones lp root sys uucp |
Controlling Access to the crontab Command
You can control access to the crontab command by using two files in the /etc/cron.d directory: cron.deny and cron.allow. These files permit only specified users to perform the crontab command tasks such as creating, editing, displaying, or removing their own crontab files.
The cron.deny and cron.allow files consist of a list of user names, one per line. These access control files work together as follows:
If cron.allow exists, only the users listed in this file can create, edit, display, or remove crontab files.
If cron.allow does not exist, all users can submit crontab files, except for users listed in cron.deny.
If neither cron.allow nor cron.deny exists, superuser privileges are required to run the crontab command.
Superuser privileges are required to edit or create the cron.deny and cron.allow files.
The cron.deny file, created during SunOS software installation, contains the following user names:
$ cat /etc/cron.d/cron.deny daemon bin smtp nuucp listen nobody noaccess |
None of the user names in the default cron.deny file can access the crontab command. You can edit this file to add other user names that will be denied access to the crontab command.
No default cron.allow file is supplied. So, after Solaris software installation, all users (except the ones listed in the default cron.deny file) can access the crontab command. If you create a cron.allow file, only these users can access the crontab command.