Cron jobs are perfect for executing a specific task or script at a scheduled time or different time periods.
Cron jobs can be run hourly, daily, weekly and monthly.
Cron configuration file is located:
/etc/crontab
This file should look like this:
# Example of job definition: # .---------------- minute (0 - 59) # | .------------- hour (0 - 23) # | | .---------- day of month (1 - 31) # | | | .------- month (1 - 12) OR jan,feb,mar,apr ... # | | | | .---- day of week (0 - 6) (Sunday=0 or 7) OR sun,mon,tue,wed,thu,fri,sat # | | | | | # * * * * * user-name command to be executed
Execute a job every X minutes
*/5 * * * * /path/to/script/script.sh
Use */10 for every 10 minutes, */15 for every 15 minutes… and so forth..
Execute a job every X hours
0 */5 * * * /path/to/script/script.sh
Use */2 for every 2 hours, */3 for every 3 minutes… and so forth..
Execute a job every Xth day of the week
Lets assume you want to execute a cron job every Wednesday at midnight:
0 0 * * 3 /path/to/script/script.sh
or
0 0 * * Wed /path/to/script/script.sh
You can use the corresponding number or the three letters for each weekday:
0=Sun 1=Mon 2=Tue 3=Wed 4=Thu 5=Fri 6=Sat
Please note that numbers starts with 0 for Monday, and not 1.
Execute a job every X months
You need to specify the what specific month or months you want to job to be executed. Like January and September:
0 0 1 1,9 * /path/to/script/script.sh
or
0 0 1 Jan,Sep * /path/to/script/script.sh
If you only want January and September, you should use a comma. If you want the job to be executed starting January and ending September, you need to use this format: 1-9.
Owl Dev X 