**** Introduction ****
either do or do the operation and maintenance of the development program ape, crontab command is a command must be used, especially for the operation and maintenance of the person, automated operation and maintenance, crontab also belong to one. However, it is common to record the timing crontab processing command.
**** **** crontab Introduction to
short it, crontab is a custom timer.
**** **** crontab configuration file
- First:
/var/spool/cron/
The directory is stored under each user (including root) crontab task of the file name with your name - Second:
/etc/cron.d/
This directory is used to store any crontab files or scripts to be executed.
**** **** crontab Time Description
# .---------------- minute (0 - 59)
# | .------------- hour (0 - 23)
# | | .---------- day of month (1 - 31)
# | | | .------- month (1 - 12) OR jan,feb,mar,apr ...
# | | | | .---- day of week (0 - 6) (Sunday=0 or 7) OR
#sun,mon,tue,wed,thu,fri,sat
# | | | | |
# * * * * * command to be executed
minute: in the representative fraction of one hour, range 0-59.
hour: represents the first few hours of the day, range 0-23.
mday: represents the first day of the month, range 1-31.
month: the first few months of the year represents the range of 1-12.
wday: on behalf of the week, range 0-7 (0 and 7 are Sunday).
who: To what capacity the instruction is executed when you use the crontab -e, do not add this field.
command: command to be executed.
**** **** crontab service status
sudo service crond start #启动服务
sudo service crond stop #关闭服务
sudo service crond restart #重启服务
sudo service crond reload #重新载入配置
sudo service crond status #查看服务状态
**** **** crontab command
reassigned crontab scheduled tasks list file
crontab $filepath
View crontab regular tasks
crontab -l
Edit Delete scheduled task - Add - Edit]
crontab -e
Add regular tasks [Recommended]
Step-One: [edit task scripts sub-directory store] [ex: backup.sh]
Step-Two: [edit time file naming conventions: backup.cron]
Step-Three: crontab command added to the systemcrontab backup.cron
Step -Four: View crontab listcrontab -l
Examples **** **** time the crontab
# 每天早上6点
0 6 * * * echo "Good morning." >> /tmp/test.txt //注意单纯echo，从屏幕上看不到任何输出，因为cron把任何输出都email到root的信箱了。
# 每两个小时
0 */2 * * * echo "Have a break now." >> /tmp/test.txt
# 晚上11点到早上8点之间每两个小时和早上八点
0 23-7/2，8 * * * echo "Have a good dream" >> /tmp/test.txt
# 每个月的4号和每个礼拜的礼拜一到礼拜三的早上11点
0 11 4 * 1-3 command line
# 1月1日早上4点
0 4 1 1 * command line SHELL=/bin/bash PATH=/sbin:/bin:/usr/sbin:/usr/bin MAILTO=root //如果出现错误，或者有数据输出，数据作为邮件发给这个帐号 HOME=/
# 每小时（第一分钟）执行/etc/cron.hourly内的脚本
01 * * * * root run-parts /etc/cron.hourly
# 每天（凌晨4：02）执行/etc/cron.daily内的脚本
02 4 * * * root run-parts /etc/cron.daily
# 每星期（周日凌晨4：22）执行/etc/cron.weekly内的脚本
22 4 * * 0 root run-parts /etc/cron.weekly
# 每月（1号凌晨4：42）去执行/etc/cron.monthly内的脚本
42 4 1 * * root run-parts /etc/cron.monthly
# 注意: "run-parts"这个参数了，如果去掉这个参数的话，后面就可以写要运行的某个脚本名，而不是文件夹名。
# 每天的下午4点、5点、6点的5 min、15 min、25 min、35 min、45 min、55 min时执行命令。
5，15，25，35，45，55 16，17，18 * * * command
# 每周一，三，五的下午3：00系统进入维护状态，重新启动系统。
00 15 * *1，3，5 shutdown -r +5
# 每小时的10分，40分执行用户目录下的innd/bbslin这个指令：
10，40 * * * * innd/bbslink
# 每小时的1分执行用户目录下的bin/account这个指令：
1 * * * * bin/account
# 每天早晨三点二十分执行用户目录下如下所示的两个指令（每个指令以;分隔）：
203 * * * （/bin/rm -f expire.ls logins.bad;bin/expire$#@62;expire.1st）
