Cron is most suitable for scheduling repetitive tasks. Scheduling one-time tasks can be accomplished using the.
Min Hour Day Mon Weekday
* * * * * command to be executed
┬ ┬ ┬ ┬ ┬
│ │ │ │ └─ Day of Week (0=Sun .. 6=Sat)
│ │ │ └────── Month (1..12)
│ │ └─────────── Day of Month (1..31)
│ └──────────────── Hour (0..23)
└───────────────────── Minute (0..59)
Minute — 0 - 59 — , - * /
Hour — 0 - 23 — , - * /
Day of Month — 1 - 31 — , - * ? / L W
Month — 1 - 12 — , - * /
Day of Week — 0 - 6 — , - * ? / L #
*/15 * * * * — Every 15 mins
0 * * * * — Every hour
0 */2 * * * — Every 2 hours
15 2 * * * — At 2:15AM of every day
15 2 * * ? — At 2:15AM of every day
10 9 * * 5 — At 9:10AM of every Friday
0 0 * * 0 — At midnight of every Sunday
15 2 * * 1L — At 2:15am on the last monday of every month
15 0 * * 4#2 — At 00:15am on the second thursday of every month
0 0 1 * * — Every 1st of month (monthly)
0 0 1 1 * — Every 1st of january (yearly)
@reboot — Every reboot (non-standard)
@reboot — Run once, at system startup (non-standard)
@yearly — Run once every year, "0 0 1 1 *" (non-standard)
@annually — (same as @yearly) (non-standard)
@monthly — Run once every month, "0 0 1 * *" (non-standard)
@weekly — Run once every week, "0 0 * * 0" (non-standard)
@daily — Run once each day, "0 0 * * *" (non-standard)
@midnight — (same as @daily) (non-standard)
@hourly — Run once an hour, "0 * * * *" (non-standard)
crontab -e — Edit or create a crontab file if doesn’t already exist.
crontab -l — Display the crontab file.
crontab -r — Remove the crontab file.
crontab -v — Display the last time you edited your crontab file.(non-standard)
Asterik(*) — Matches all values in the field or any possible value.
Hyphen(-) — Used to define a range.Ex: 1-5 in 5th field(Day Of Week) Every Weekday i.e., Monday to Friday
Slash (/) — 1st field(Minute) /15 meaning every fifteen minute or increment of range.
Comma (,) — Used to separate items.Ex: 2,6,8 in 2nd fields(Hour) executes at 2am,6am and 8am
L — It is allowed only for Day of Month or Day Of Week field, 2L in Day of week indicates Last tuesday of every month
Hash (#) — It is allowed only for Day Of Week field, which must be followed within range of 1 to 5. For example, 4#1 means "The first Thursday" of given month.
Question mark (?) — Can be instead of '*' and allowed for Day of Month and Day Of Week. Usage is restricted to either Day of Month or Day Of Week in a cron expression.