Crontab
A software utility to a Linux operating system or server for a job that is to be executed at a specified time.
A Linux system admin knows the importance of running the routine maintenance jobs in the background automatically. Linux Cron utility is an effective way to schedule a routine background job at a specific time and/or day on an on-going basis.
Often, you will want to use cron to schedule daily, weekly, hourly etc... tasks on your Linux system. Ok, so cron is what is used on your Linux system to schedule repeating events. It’s used to rotate logs, run clean-up scripts, and anything else you can think of that you’d want to schedule.
To View Crontab
To Edit Crontab
Edit another user's crontab
View another user's crontab
Crontab Format
Example
This crontab executes the "/root/backup.sh" script at 3 PM on every day.
Some Another Example
Also, You can run multiple scripts or command in one crontab using (;) semicolumn.
A software utility to a Linux operating system or server for a job that is to be executed at a specified time.
A Linux system admin knows the importance of running the routine maintenance jobs in the background automatically. Linux Cron utility is an effective way to schedule a routine background job at a specific time and/or day on an on-going basis.
Often, you will want to use cron to schedule daily, weekly, hourly etc... tasks on your Linux system. Ok, so cron is what is used on your Linux system to schedule repeating events. It’s used to rotate logs, run clean-up scripts, and anything else you can think of that you’d want to schedule.
To View Crontab
# crontab -l
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To Edit Crontab
# crontab -e
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Edit another user's crontab
# crontab -u serverkaka -e
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View another user's crontab
# crontab -u serverkaka -l
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Crontab Format
Minute Hour DOM Month DOW Command
|
Field
|
Allowed Values
|
Minute
|
0 – 59
|
Hour
|
0 – 23
|
Day of month
|
1 – 31
|
Month
|
1 – 12
|
Day of week
|
0 – 7
|
String
|
Crontab Value
|
Yearly
|
0 0 1 1 *
|
Monthly
|
0 0 1 * *
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Weekly
|
0 0 * 0 0
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Daily
|
0 0 * * *
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Hourly
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0 * * * *
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Example
Minute
|
Hour
|
Day of Month
|
Month
|
Day of Week
|
Command
|
0 – 59
|
0 – 23
|
1 – 31
|
1 – 12
|
0 – 6
|
|
0 15 * * * /root/backup.sh
|
|||||
This crontab executes the "/root/backup.sh" script at 3 PM on every day.
Some Another Example
0 23 * * * /root/backup.sh
This Script run at everyday 11:00 PM
|
0 11,23 * * * /root/backup.sh
This Script run at everyday 11:00 AM and 11:00 PM
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0 7 * * 0 /root/backup.sh
This Script run at every Sunday morning 7 AM
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0 7 * 5 6 /root/backup.sh
This Script run at every Saturday of May month at morning 7 AM
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15 7 * 5 6 /root/backup.sh
This Script run at every Saturday of May month at morning 7:15 AM
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* * * * * /root/backup.sh
This Script run at every minutes
|
*/5 * * * * /root/backup.sh
This Script run at every 5 minutes
|
0 17 * * 1,5 /root/backup.sh
This Script run at every 5:00 PM at Monday and Friday
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*/5 * * * * /root/backup.sh
This Script run at every 5 minutes
|
0 */5 * * * /root/backup.sh
This Script run at every 5 hours
|
* * * * * sleep 30; /root/backup.sh
This Script run at every 30 seconds
|
0 * * * * /root/backup.sh
OR
@hourly /root/backup.sh
This Script run at every hour
|
0 0 * * * /root/backup.sh
OR
@daily /root/backup.sh
This Script run at daily
|
0 0 * 0 0 /root/backup.sh
OR
@weekly /root/backup.sh
This Script run at every week
|
0 0 1 * * /root/backup.sh
OR
@monthly /root/backup.sh
This Script run at every month
|
0 0 1 1 * /root/backup.sh
OR
@yearly /root/backup.sh
This Script run at every year
|
Also, You can run multiple scripts or command in one crontab using (;) semicolumn.
0 0 * * * /root/backup.sh; /home/script.sh
This Script run at daily
|
Also, You can run script on system reboot
@reboot /root/backup.sh
This Script run on every system reboot
|
