Teach you how to set up the server to automatically restart using Linux

As programmers, we have all used Linux. We all know that Linux is mainly used for servers. In this article, we will teach you a technique to set up automatic server restart under Linux. I hope it will be useful for everyone's work.

The steps are as follows:

The steps to automatically restart at 3 a.m. on the 1st of each month are as follows:

1. Log in with the root account;

2. Open Terminal window;

3. Enter "crontab -e"

4. Press the Insert key.

5. Enter "0 3 1 * * reboot"

6. Press the esc key.

7. Enter ":wq" and press Enter.

The above input content can be queried through the "crontab -l" command.

Automatically restart at 3 a.m. every Monday

1. Log in with the root account;

2.Open the terminal window;

3.Enter " crontab -e"

4. Press the Insert key.

5. Enter "0 3 * * 1 reboot"

6. Press the esc key.

7. Enter ":wq" and press Enter.

The above input content can be queried through the "crontab -l" command.

Linux system scheduled restart

After successfully logging in to the background using the SSH tool, run the following command: crontab -e

Then insert the following content into the document as needed:

0 4 * * * /sbin/reboot (0 4 means restarting at 4 am every day.. 0 3 means 3 am..)

: After saving and exiting wq, execute the following command to restart the crond service. Yes.

/sbin/service crond stop //Close the service

/sbin/service crond restart //Restart the service

/sbin/service crond reload //Reload Enter the configuration

You can also start this service automatically when the system starts:

Add at the end of the /etc/rc.d/rc.local script:

/sbin/service crond start

Now that the Cron service is already in the process, we can use this service. The Cron service provides the following interfaces for everyone to use:

1. Directly use the crontab command to edit

The cron service provides the crontab command to set the cron service. The following are some parameters and instructions for this command:

crontab -u / /Set the cron service of a certain user. Generally, the root user needs this parameter when executing this command.

crontab -l //List the details of the cron service of a certain user.

crontab -r //Delete the cron service of each user

crontab -e //Edit the cron service of a certain user

For example, root checks his own cron settings: crontab -u root -l

Another example, root wants to delete fred's cron settings: crontab -u fred -r

When editing the cron service, the edited content has some formats and conventions, enter: crontab -u root -e

Enter vi editing mode. The edited content must conform to the following format: */1 * * * * ls >> /tmp/ls.txt

The first part of this format One part is the setting of the time, and the latter part is the command to be executed. If there are too many commands to be executed, you can write these commands into a script, and then just call the script directly here. Remember to write when calling The full path to the command. We have a certain agreement on setting the time. The first five * signs represent five numbers. The value range and meaning of the numbers are as follows:

minutes (0-59)

hours (0 -23)

Date(1-31)

Month(1-12)

Week(0-6)//0 represents Sunday

In addition to numbers, there are several special symbols: "*", "/" and "-", ",". * represents all numbers within the value range, "/" represents the meaning of every, "*/5 "represents every 5 units,"-"represents from a certain number to a certain number,","separates several discrete numbers. Here are a few examples to illustrate the problem:

Every morning at 6 o'clock

0 6 * * * echo "Good morning." >> /tmp/test.txt //Pay attention to simple echo , no output can be seen on the screen, because cron emails any output to the root mailbox.

Every two hours

0 */2 * * * echo "Have a break now." >> /tmp/test.txt

11pm Every two hours between 8am and 8am, 8am

0 23-7/2, 8 * * * echo "Have a good dream:)" >> /tmp/test.txt

On the 4th of every month and at 11 a.m. from Monday to Wednesday every week

0 11 4 * 1-3 command line

January 1 At 4 o'clock in the morning on the same day

0 4 1 1 * command line

Each time after editing a user's cron settings, cron automatically generates a new username under /var/spool/cron For files with the same name, the user's cron information is recorded in this file. This file cannot be edited directly and can only be edited with crontab -e. After cron starts, it reads this file every time and checks whether the commands in it need to be executed. Therefore, there is no need to restart the cron service after modifying this file.

2. Edit the /etc/crontab file to configure cron

The cron service not only needs to read all the files in /var/spool/cron once every minute, but also needs to read Once /etc/crontab, so we configure this file to also use the cron service to do something. Configuration with crontab is for a certain user, while editing /etc/crontab is a task for the system. The file format of this file is:

SHELL=/bin/bash

PATH=/sbin:/bin:/usr/sbin:/usr/bin

MAILTO= root //If an error occurs or data is output, the data will be sent to this account as an email

HOME=/ //The path where the user runs, this is the root directory

# run-parts

01 * * * * root run-parts /etc/cron.hourly / /Execute the scripts in /etc/cron.hourly every hour

02 4 * * * root run-parts /etc/cron.daily //Execute the scripts in /etc/cron.daily every day

22 4 * * 0 root run-parts /etc/cron.weekly //Execute the script in /etc/cron.weekly every week

42 4 1 * * root run-parts /etc/ cron.monthly //Execute the script in /etc/cron.monthly every month

Please pay attention to the "run-parts" parameter. If you remove this parameter, you can write a certain script to be run later. The script name, not the folder name.

The above content is the technique for setting up the server to automatically restart under Linux. I hope that after reading this article, you will master this technique and be able to set up your own server to automatically restart.

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