在本文中，我们将教您–如何安排玉米作业在特定时间执行。
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作业列表，请运行以下命令-
# crontab -l no crontab for root
要添加新的cron作业，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
Cron的基本用法是在特定时间执行作业，如下所示。这将在4月20日下午06:40执行完整的备份Shell脚本（完整备份）。
40 18 20 04 * /home/backups/full-backup
40 – 40th Minute 18 – 06 PM 20 – 20th Day 04 – 4th Month (April) * – Every day of the week
在配置结束时，您将能够每天在特定时间运行脚本或命令，这样我们可以使用逗号分隔的值指定多次执行的时间。