Installation CronTab
CentOS comes with a CronTab if necessary Baidu, you know
CentOS installation CronTab
vixie-cron cron package is the main
yum -y install vixie-cron
crontabs package is used to install, uninstall, or list the program used to drive the cron daemon table
yum -y install crontabs
Ubuntu installation CronTab
apt-get install cron
CronTab use and interpretation
The syntax used in Centos
crontab -lView all scheduled tasks
crontab -eto modify a scheduled task
service crond startLaunch scheduled task
service crond restartto restart the scheduled task
service crond reloadreloads the scheduled task
The syntax used in Ubuntu
service cron startLaunch scheduled task
service cron restartto restart the scheduled task
service cron reloadreloads the scheduled task
If the first use of this command will let you choose a text editor, I chose vim
if want to change:select-editor
CronTab syntax
* * * * * date >> /tmp/date.txt
| * | * | * | * | * | date >> /tmp/date.txt |
|---|---|---|---|---|---|
| minute | hour | day | month | week | command |
| minute | hour | A few numbers | A few months | week | Command to be executed |
Use Cases
| script | Explanation |
|---|---|
* */1 * * * /service/l-zm/request.sh |
Every hour |
0 */3 * * * sh /opt/***.sh |
Every three hours to execute the script |
01 * * * * root run-parts /etc/cron.hourly |
Execute scripts in a directory /etc/cron.hourly per hour |
01 * * * * root run-parts /etc/cron.hourly |
Execute scripts in a directory /etc/cron.hourly per hour |
3,15 * * * * /service/l-zm/request.sh |
Performing the third hour and 15 minutes |
3,15 8-11 * * * /service/l-zm/request.sh |
3 and performed in the first 15 minutes of 8:00 to 11:00 |
3,15 8-11 */2 * * date >> /tmp/date.txt |
3 and 15 minutes every day 8:00 to 11:00 is performed |
3,15 8-11 * * 1 date >> /tmp/date.txt |
Each of the third and 15 minutes Monday 8:00 to 11:00 of execution |
30 21 * * * /service/l-zm/request.sh |
21:30 night |
45 4 1,10,22 * * /service/l-zm/request.sh |
1 month, 10, 22 May 4:45 |
10 1 * * 6,0 /service/l-zm/request.sh |
Every Saturday, Sunday 1:10 |
0,30 18-23 * * * /service/l-zm/request.sh |
Day 18: 00-23: 00 every 30 minutes |
0 23 * * 6 /service/l-zm/request.sh |
Every Saturday night 11: 00 pm |
* 23-7/1 * * * /service/l-zm/request.sh |
Between 11 pm to 7 am, every hour |
0 11 4 * mon-wed /service/l-zm/request.sh |
No. 4 month and every Monday to Wednesday 11:00 |
0 4 1 jan * /service/l-zm/request.sh |
January 1st of 4:00 |
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Execute once per second
*/1 * * * * sleep 0s;date >> /tmp/date.txt
*/1 * * * * sleep 1s; date >> /tmp/date.txt
*/1 * * * * sleep 2s; date >> /tmp/date.txt
*/1 * * * * sleep 3s; date >> /tmp/date.txt
*/1 * * * * sleep 4s; date >> /tmp/date.txt
*/1 * * * * sleep 5s; date >> /tmp/date.txt
*/1 * * * * sleep 6s; date >> /tmp/date.txt
*/1 * * * * sleep 7s; date >> /tmp/date.txt
*/1 * * * * sleep 8s; date >> /tmp/date.txt
*/1 * * * * sleep 9s; date >> /tmp/date.txt
*/1 * * * * sleep 10s; date >> /tmp/date.txt
*/1 * * * * sleep 11s; date >> /tmp/date.txt
*/1 * * * * sleep 12s; date >> /tmp/date.txt
*/1 * * * * sleep 13s; date >> /tmp/date.txt
*/1 * * * * sleep 14s; date >> /tmp/date.txt
*/1 * * * * sleep 15s; date >> /tmp/date.txt
*/1 * * * * sleep 16s; date >> /tmp/date.txt
*/1 * * * * sleep 17s; date >> /tmp/date.txt
*/1 * * * * sleep 18s; date >> /tmp/date.txt
*/1 * * * * sleep 19s; date >> /tmp/date.txt
*/1 * * * * sleep 20s; date >> /tmp/date.txt
*/1 * * * * sleep 21s; date >> /tmp/date.txt
*/1 * * * * sleep 22s; date >> /tmp/date.txt
*/1 * * * * sleep 23s; date >> /tmp/date.txt
*/1 * * * * sleep 24s; date >> /tmp/date.txt
*/1 * * * * sleep 25s; date >> /tmp/date.txt
*/1 * * * * sleep 26s; date >> /tmp/date.txt
*/1 * * * * sleep 27s; date >> /tmp/date.txt
*/1 * * * * sleep 28s; date >> /tmp/date.txt
*/1 * * * * sleep 29s; date >> /tmp/date.txt
*/1 * * * * sleep 30s; date >> /tmp/date.txt
*/1 * * * * sleep 31s; date >> /tmp/date.txt
*/1 * * * * sleep 32s; date >> /tmp/date.txt
*/1 * * * * sleep 33s; date >> /tmp/date.txt
*/1 * * * * sleep 34s; date >> /tmp/date.txt
*/1 * * * * sleep 35s; date >> /tmp/date.txt
*/1 * * * * sleep 36s; date >> /tmp/date.txt
*/1 * * * * sleep 37s; date >> /tmp/date.txt
*/1 * * * * sleep 38s; date >> /tmp/date.txt
*/1 * * * * sleep 39s; date >> /tmp/date.txt
*/1 * * * * sleep 40s; date >> /tmp/date.txt
*/1 * * * * sleep 41s; date >> /tmp/date.txt
*/1 * * * * sleep 42s; date >> /tmp/date.txt
*/1 * * * * sleep 43s; date >> /tmp/date.txt
*/1 * * * * sleep 44s; date >> /tmp/date.txt
*/1 * * * * sleep 45s; date >> /tmp/date.txt
*/1 * * * * sleep 46s; date >> /tmp/date.txt
*/1 * * * * sleep 47s; date >> /tmp/date.txt
*/1 * * * * sleep 48s; date >> /tmp/date.txt
*/1 * * * * sleep 49s; date >> /tmp/date.txt
*/1 * * * * sleep 50s; date >> /tmp/date.txt
*/1 * * * * sleep 51s; date >> /tmp/date.txt
*/1 * * * * sleep 52s; date >> /tmp/date.txt
*/1 * * * * sleep 53s; date >> /tmp/date.txt
*/1 * * * * sleep 54s; date >> /tmp/date.txt
*/1 * * * * sleep 55s; date >> /tmp/date.txt
*/1 * * * * sleep 56s; date >> /tmp/date.txt
*/1 * * * * sleep 57s; date >> /tmp/date.txt
*/1 * * * * sleep 58s; date >> /tmp/date.txt
*/1 * * * * sleep 59s; date >> /tmp/date.txt
如果每秒没有循环连续 可以试试把 sleep 0s 删除, 在最后添加 sleep 60s (CentOS 和 Ubuntu 下不一样)
Linux CronTab