Linux Command: Use crontab

Linux Command: crontab uses -- Linux general technology-Linux technology and application information. The following is a detailed description. In Windows, there is a "Task Plan", and a shutdown file can be used as a bat file for Timed shutdown. in Linux, there is also a cron, whose configuration file is named crontab, we can use the crontab command to configure it.

Format
Second hour day month week [user name] command
Seconds 0-59
Hour 0-24
Day 1-31
Month 1-12
Week 0-6 (0 represents Sunday)

* It can match all numbers, that is, all time points.
-Use two integers separated by short lines to match the time points of these two values, for example, 0-9. In addition, use/to implement execution at specified intervals, for example, 0-59/30 is at, 4... these time points are executed.
, You can use commas to match any listed range or integer, such as 0-12, 14.
If the command is long, use the percent sign (%) to wrap the line.

Let's talk less. First, # crontab-h. I use Fedora 7, which is shown as follows:

Usage: crontab [-u user] file
Crontab [-u user] [-e |-l |-r]
(Default operation is replace, per 1003.2)
-E (edit user's crontab)
-L (list user's crontab)
-R (delete user's crontab)
-I (prompt before deleting user's crontab)
-S (selinux context)

-U specifies the user, which is the current user by default.
-E Editing: vim is used by default. If you are not familiar with vim, you can find a solution.
-L list timelines
-R Delete
-I prompts the user during the deletion.
-E is related to selinux.

The last two items are generally unavailable, so you don't have to worry about it. It is useful to have a crontab file. You can write a configuration in a file by yourself, and then use this command to write the configuration into crontab, -l you can see the effect. You may ask where these configurations are saved. In fact, there are three places where these configuration files are stored:/var/spool/cron;/etc/cron. d;/etc/crontab. Generally, we use the first one. So if you have configured crontab, you will find a file named after the user name under/var/spool/cron, you can directly open the editing without the crontab-e command, and the effect is the same. On the GUI, you can use other tools, such as gedit.