如何在 Linux 中创建 Cron 任务并在指定时间执行
在本文中,我们将教您如何安排一个将在指定时间执行的 corn 任务。
Cron 任务的一般语法
MIN HOUR Day of month Month Day of Week Command 0-59 0-23 1-31 1-12 0-6 linux command or script
要查看机器上存在的 Cron 任务列表,请运行以下命令 –
# crontab -l no crontab for root
要添加新的 Cron 任务,请运行以下命令 –
#crontab -e no crontab for root - using an empty one Select an editor. To change later, run 'select-editor'. 1. /bin/ed 2. /bin/nano <---- easiest 3. /usr/bin/vim.basic 4. /usr/bin/vim.tiny Choose 1-4 [2]:2 # 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
为某个特定时间安排任务
Cron 的基本用法是按如下所示在某个指定时间执行任务。这将在 4 月 20 日下午 6:40 执行全备份 shell 脚本 (full-backup)。
40 18 20 04 * /home/backups/full-backup
解释
40 – 40th Minute 18 – 06 PM 20 – 20th Day 04 – 4th Month (April) * – Every day of the week
在配置的最后,你将能够在每一天的某个特定时间运行一个脚本或命令,比如这样,我们可以使用逗号分隔值指定多个执行时间。
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