To list current crontabs:
# crontab -l
You can create a crontab file by entering the following terminal command:
# crontab -e
A crontab file has six fields for specifying minute, hour, day of month, month, day of week and the command to be run at that interval:
################################################################# #minute (0-59), # #| hour (0-23), # #| | day of the month (1-31), # #| | | month of the year (1-12), # #| | | | day of the week (0-6 with 0=Sun)# #| | | | | commands # #################################################################
Some examples:
* * * * * #Runs every minute
*/5 * * * * #Runs at every 5 minutes
30 * * * * #Runs at 30 minutes past the hour
45 6 * * * #Runs at 6:45 am every day
45 18 * * * #Runs at 6:45 pm every day
00 1 * * 0 #Runs at 1:00 am every Sunday
00 1 * * 7 #Runs at 1:00 am every Sunday
00 1 * * Sun #Runs at 1:00 am every Sunday
30 8 1 * * #Runs at 8:30 am on the first day of every month
00 0-23/2 02 07 * #Runs every other hour on the 2nd of July
You can also use some special strings:
*/5 * * * *
30 * * * *
45 6 * * *
45 18 * * *
00 1 * * 0
00 1 * * 7
00 1 * * Sun
30 8 1 * *
00 0-23/2 02 07 *
You can also use some special strings:
@reboot #Runs at boot
@yearly #Runs once a year [0 0 1 1 *]
@annually #Runs once a year [0 0 1 1 *]
@monthly #Runs once a month [0 0 1 * *]
@weekly #Runs once a week [0 0 * * 0]
@daily #Runs once a day [0 0 * * *]
@midnight #Runs once a day [0 0 * * *]
@hourly #Runs once an hour [0 * * * *]
You can use multiple commands for the same crontab:
Specifying a crontab file to use
Example:
-would set Tux's crontab file to that of the file named "crontab" residing in Tux's home directory.
To remove a crontab file for current user:
@yearly
@annually
@monthly
@weekly
@daily
@midnight
@hourly
You can use multiple commands for the same crontab:
@daily &&
Specifying a crontab file to use
# crontab -u
Example:
# crontab -u tux ~/crontab
-would set Tux's crontab file to that of the file named "crontab" residing in Tux's home directory.
To remove a crontab file for current user:
# crontab -r
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