Cron

Format

{: .-two-column}

Format

Min  Hour Day  Mon  Weekday

{: .-setup}

*    *    *    *    *  command to be executed

┬    ┬    ┬    ┬    ┬
│    │    │    │    └─  Weekday  (0=Sun .. 6=Sat)
│    │    │    └──────  Month    (1..12)
│    │    └───────────  Day      (1..31)
│    └────────────────  Hour     (0..23)
└─────────────────────  Minute   (0..59)

{: .-setup.-box-chars}

Operators

Operator	Description
*	all values
,	separate individual values
-	a range of values
/	divide a value into steps

Special strings

String	Description
@reboot	every rebot
@hourly	once every hour - same as 0 * * * *
@daily	once every day - same as 0 0 * * *
@midnight	once every midnight - same as @daily
@weekly	once every week - same as 0 0 * * 0
@monthly	once every month - same as 0 0 1 * *
@yearly	once every year - same as 0 0 1 1 *

Examples

Example	Description
0 * * * *	every hour
*/15 * * * *	every 15 mins
0 */2 * * *	every 2 hours
0 18 * * 0-6	every week Mon-Sat at 6pm
10 2 * * 6,7	every Sat and Sun on 2:10am
0 0 * * 0	every Sunday midnight

Crontab

# Adding tasks easily
echo "@reboot echo hi" | crontab

# Open in editor - optional for another user
crontab -e [-u user]

# List tasks - optional for another user
crontab -l [-u user]

# Delete crontab file - optional for another user
crontab -r [-u user]