Implement scheduled tasks in CentOs 7.0 (access webpages regularly)

Implement scheduled tasks in CentOs 7.0 (access webpages regularly)

1. Enter crontab-e to go to the editing page.
2. Input/2* ** Curlhttp: // www.baidu.com, indicating that the webpage is accessed every two minutes
3. Save and exit, and then start the service using service crond start.
4. Set chkconfig crond on to start automatically
5,
Basic Format:
* *** Command
Hour, day, month, and week commands
The 1st column indicates minute 1 ~ 59 per minuteOr/1 indicates
The first column indicates the hour 1 ~ 23 (0 indicates 0 points)
The 3rd column indicates the date 1 ~ 31
The 4th column indicates the month 1 ~ 12
The Identification Number of column 5th is from day of the week to day ~ 6 (0 indicates Sunday)

30 21 ***/usr/local/etc/rc. d/lighttpd restart
The preceding example indicates restarting apache at every night.

Crond does not support accurate to seconds