cron & crontab

cron和crontab命令

cron

daemon to execute shceduled commands

crontab

mantain crontab files for individual users

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#显示crontab文件
$ crontab -l

#编辑crontab文件, 如果没有会自动创建
$ crontab -e

#删除crontab文件
$ crontab -r

#删除crontab文件前提醒用户
$ crontab -ri

一个crontab文件实例:

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# Edit this file to introduce tasks to be run by cron.
# 
# Each task to run has to be defined through a single line
# indicating with different fields when the task will be run
# and what command to run for the task
# 
# To define the time you can provide concrete values for
# minute (m), hour (h), day of month (dom), month (mon),
# and day of week (dow) or use '*' in these fields (for 'any').# 
# Notice that tasks will be started based on the cron's system
# daemon's notion of time and timezones.
# 
# Output of the crontab jobs (including errors) is sent through
# email to the user the crontab file belongs to (unless redirected).
# 
# For example, you can run a backup of all your user accounts
# at 5 a.m every week with:
# 0 5 * * 1 tar -zcf /var/backups/home.tgz /home/
# 
# For more information see the manual pages of crontab(5) and cron(8)
# 
# m h  dom mon dow   command

#整点锁屏休息, 其中gnome-screensaver-command -l为立刻锁屏命令
#minute=0, hour=*,day of month=*,month=*, day of week=*
0 * * * * DISPLAY=:0 gnome-screensaver-command -l