Recurring schedule (a cron daemon):

Recurring Plan (a cron daemon): [email protected]:/etc# Ps-ef |grep cronroot903 1 0 16:25? 00:00:00/usr/sbin/cron-Froot16162 6459 0 22:08 pts/1 00:00:00 grep--color=Auto Croncron is a daemon that can be executed periodically based on the combination of time, date, month, and week. (Can be stopped and restarted) [email protected]:/etc# Service cron Stop[email protected]:/etc# Ps-ef |grep cronroot16212 6459 0 22:09 pts/1 00:00:00 grep--color=Auto Cron[email protected]:/etc# Service cron Start[email protected]:/etc# Ps-ef |grep cronroot16252 1 3 22:09? 00:00:00/usr/sbin/cron-Froot16263 6459 0 22:09 pts/1 00:00:00 grep--color=Auto Cron (start in different modes) [email protected]:/# service cron status Cron.service-Regular Background Program processing daemon loaded:loaded (/lib/systemd/system/cron.service; vendor Preset:ena Active:active (running) since four2018-02-15 22:09:54PST; 17min ago Docs:man:cron (8) Main PID:16252(cron) Tasks:1Memory:1. 1M cpu:30ms CGroup:/system.slice/cron.service└─16252/usr/sbin/cron-F[email protected]:/# sysv-rc-conf--List Croncron2:on 3:on 4:on 5:on

* Indicates that this time does not exist (0 and 7 for Sunday). January 2 3:50 Go to execute a program. This time is taken from the current operating system.

[Email protected]:/# crontab-L (View time plan) No crontab forRoot (no executable time scheduled task for root account) [email protected]:/# crontab-e (Call text edit, edit time Plan)*/1 * * * * echo "Yowen" >>/yw/cron.txt (print one output per minute) [email protected]:/# crontab-L (There is a time plan) LS1 * * * * echo "Yowen" >>/yw/Cron.txt[email protected]:/# service Cron Reload (restart daemon cron)* Reloading configuration files forperiodic command Scheduler cron [OK] [email protected]:/yw# Service Cron Restart (create 2 accounts) [email protected]:/yw# useradd zhangsan[email protected]:/yw# useradd lisi[email protected]:/yw# passwd zhangsanenterNewUNIX Password:retypeNewUNIX Password:passwd:password updated successfully[email protected]:/yw# passwd lisienterNewUNIX Password:retypeNewUNIX Password:passwd:password updated successfully[email protected]:/# crontab-r (delete task) [email protected]:/yw# Service cron Restart (delete task, also restart) [email protected]:/etc# vim Cron.deny (account Zhangsan cannot use cron Scheduled Tasks) Zhangsan[email protected]:~$ Su-Zhangsanpassword:no directory, logging in with HOME=/$ crontabyou (Zhangsan) is not allowed ThisProgram (crontab) See Crontab (1) fo

Cron mainly depends on the time setting and User Level control.

Recurring schedule (a cron daemon):