Crontab Timing Scheduling

First, configure the environment

System: CentOS

First Execute:

Crontab-  L  

The system cannot find the command "-bash:crontab:command not found" if it appears

You need to install the package "Vixie-cron", "Crontab"

Yum Install   -yvixie-yuminstall   crontab

Execute crontab-l again, if "No crontab for Root" appears, execute CRONTAB-E create a new empty file in vi edit mode, press shift+: Exit, Hint: crontab:installing new Cront AB executes crontab-l at this time, without prompting the installation succeeds.

crontab Command Common parameters:

-e means editing the current crontab

-L indicates that the list displays the current crontab task

-R means to delete the current user's crontab

-I gives prompt message when deleting crontab

Second, configuration instructions

Basic format:

* * * * * command
Time-sharing Weekly command

The 1th column represents minutes 1~59 per minute with * or */1
The 2nd column represents the hour 1~23 (0 means 0 points)
The 3rd column represents the date 1~31
The 4th column represents the month 1~12
5th Column Identification Number Week 0~6 (0 = Sunday)
6th List of commands to run

Some examples of crontab files:

* * * */usr/local/etc/rc.d/lighttpd Restart
The above example shows that 21:30 restarts Apache per night.

4 1,10,22 * */USR/LOCAL/ETC/RC.D/LIGHTTPD restart
The above example shows that 4:45 restarts Apache on the 1, 10, and 22nd of the month.

1 * * 6,0/USR/LOCAL/ETC/RC.D/LIGHTTPD restart
The above example shows that 1:10 restarts Apache every Saturday and Sunday.

0,30 18-23 * * */usr/local/etc/rc.d/lighttpd restart
The above example shows that Apache restarts every 30 minutes from 18:00 to 23:00 every day.

0 * * 6/USR/LOCAL/ETC/RC.D/LIGHTTPD restart
The above example shows the restart of Apache every Saturday at 11:00am.

* */1 * * * */usr/local/etc/rc.d/lighttpd restart
Restart Apache every hour

* 23-7/1 * * * */usr/local/etc/rc.d/lighttpd restart
From 11 o'clock to 7 in the morning, restart Apache every hour.

0 4 * mon-wed /usr/local/etc/rc.d/lighttpd restart
4th per month with 11-point restart from Monday to Wednesday Apache

0 4 1 Jan */usr/local/etc/rc.d/lighttpd restart
4-point restart of Apache on January 1

Execute */5 every five minutes * * * *

Executes 0 per hour * * * *

Executes 0 0 * * * per day

Weekly Execution 0 0 * 0

Monthly execution 0 0 1 * *

Annual Execution 0 0 1 1 *

Third, configure timing scheduling

Execute the VI command to edit the scheduled schedule list.

Vi/etc/crontab

Execute PHP code as per minute schedule as follows

#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#Custom Schedule executes once per minute*/1 * * * * * root php/www/php/my.php>>/www/php/my.Log

Crontab Timing Scheduling