Ubuntu Set timed Tasks

Crontab-l #查看详情
Crontab-e #设置定时任务

* * * * * command
Time-sharing Weekly command
The 1th column represents minutes 1~59 per minute with * or */1
The 2nd column represents the hour 1~23 (0 means 0 points)
The 3rd column represents the date 1~31
The 4th column represents the month 1~12
5th Column Identification Number Week 0~6 (0 = Sunday)
6th List of commands to run

Example:
* * * */usr/local/etc/rc.d/lighttpd restart #每晚的21:30 restart Apache.
4 1,10,22 * */usr/local/etc/rc.d/lighttpd restart #每月1, 10, 22nd 4:45 restart Apache.
1 * * 6,0/usr/local/etc/rc.d/lighttpd restart #每周六, Sunday 1:10 restart Apache.
0,30 18-23 * * */usr/local/etc/rc.d/lighttpd restart #每天18:00 to 23:00 restart Apache every 30 minutes.
0 * * 6/usr/local/etc/rc.d/lighttpd Restart #每星期六的11: PM Restart Apache.
0 */1 * * */usr/local/etc/rc.d/lighttpd restart #每一小时重启apache
0 23-7/1 * * */usr/local/etc/rc.d/lighttpd restart #晚上11点到早上7点之间, restart Apache every hour
0 4 * mon-wed/usr/local/etc/rc.d/lighttpd restart #每月的4号与每周一到周三的11点重启apache
0 4 1 Jan */usr/local/etc/rc.d/lighttpd restart #一月一号的4点重启apache

crontab file [-u user]-replaces the current crontab with the specified files.
Crontab-[-u user]-replaces the current crontab with standard input.
crontab-1[user]-lists the user's current crontab.
crontab-e[user]-Edit user's current crontab.
crontab-d[user]-Delete the user's current crontab.
Crontab-c dir-Specifies the directory for crontab.
Format of the crontab file: M H d M D cmd.
M: Minutes (0-59).
H: Hours (0-23).
D: Day (1-31).
M: Month (1-12).
D: Day of the Week (0~6,0 is Sunday).
CMD to run the program, the program is fed into sh execution, this shell only user,home,shell these three environment variables
Description
Crontab is used to allow a user to execute a program at a fixed time or at a fixed interval, in other words, a user-like schedule. -u user refers to setting the specified
User's time table, which presupposes that you must have permission (for example, root) to specify another's time schedule. If you do not use the-u user, it means to set the
Set your own schedule.
Parameters:
CRONTAB-E: Do a text editor to set the time table, the default text editor is VI, if you want to use another text editor, please set the VISUAL environment variables first
To specify the use of that text editor (for example, Setenv VISUAL Joe)
Crontab-r: Delete the current schedule table
Crontab-l: List the current schedule
crontab file [-u user]-replaces the current crontab with the specified files.
The format of the schedule table is as follows:
F1 F2 F3 f4 f5 program
Where F1 is expressed in minutes, F2 represents hours, F3 represents the day of the month, F4 represents the month, and F5 represents the day of the one week. program says
The program of the line.
When F1 is * indicates that every minute the program,f2 is executed, the program is executed every hour, and the remainder of the analogy
When the F1 is a-B, it is executed from the time of the minute to the minute of the hour, and the F2 is a-B indicating that it is executed from the first to the first, and the remainder of the analogy
When F1 is */n, it is performed once every n minutes, and F2 is */n for every n-hour interval, with the remainder of the other analogy
When F1 is a, B, C,... A, B, C,... Minutes to execute, F2 for a, B, C,... The time indicated that the first, B, c ... Hours to execute, and the rest of the analogy
The user can also store all the settings in the file file, using the crontab file to set the time schedule.
Example:
#每天早上7点执行一次/bin/ls:
0 7 * * */BIN/LS
In December, the/usr/bin/backup is performed every 3 hours in the morning from 6 to 12.
0 6-12/3 */usr/bin/backup
Monday to Friday every 5:00 send a letter to[email protected]:
0 * * 1-5 mail-s "HI"[email protected]</tmp/maildata
Every day of the month 0:20 midnight, 2:20, 4:20 .... Perform echo "haha"
0-23/2 * * * echo "haha"
Attention:
When the program is executed at the time you specify, the system will send you a letter showing what the program is doing, and if you do not wish to receive such a letter, please leave a blank in each line
After adding >/dev/null 2>&1 can be
Example 2:
#每天早上6点10分
6 * * * Date
#每两个小时
0 */2 * * * Date
#晚上11点到早上8点之间每两个小时, 8 in the morning.
0 23-7/2,8 * * * Date
#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 4 * mon-wed date
#1月份日早上4点
0 4 1 Jan * Date
Example
$crontab-L lists the user's current crontab.

Ubuntu Set timed Tasks