Set timed tasks in linux

Set timed tasks

You can use the crontab tool in Linux to set up scheduled tasks. The specific steps are as follows:

1. Open the terminal, enter crontab -ethe command, and open the crontab editor.
2. In the editor, enter 30 9 * * 1-5 command, where 30 9 * * 1-5indicates 9:30 every Monday to Friday, and commandindicates the command to be executed.
3. After editing, save and exit the editor.

For example, if you want to execute it at 9:30 every Monday to Friday /usr/bin/python3 /home/user/main.py, you can enter the following command in the crontab editor:

#  定时 python3  main.py文件的路径
30 9 * * 1-5 /usr/bin/python3 /home/user/main.py

After saving and exiting the editor, the system will execute the command every Monday to Friday at 9:30 /usr/bin/python3 /home/user/main.py.

The role of * * * * * in crontab

* * * * *It is the time format in Linux scheduled tasks. It is composed of 5 fields, which respectively represent minutes, hours, dates, months, and days of the week. Their meanings are as follows:

• The first field indicates minutes, and the value range is 0-59;
• The second field indicates the hour, and the value range is 0-23;
• The third field represents the date, and the value range is 1-31;
• The fourth field indicates the month, and the value range is 1-12;
• The fifth field indicates the day of the week, and the value range is 0-6, where 0 means Sunday, 1 means Monday, and so on.

Each field can use the following value methods:

• *: Indicates any value, that is, does not limit the specific value;
• */n: means every n values, for example */5means every 5 values, namely 5, 10, 15, 20...;
• n1,n2,n3: Indicates that the value is n1, n2, n3 and other specified values;
• n1-n2: Indicates that the value range is from n1 to n2, for example, 1-5indicates that the values ​​are 1, 2, 3, 4, 5.

Therefore, * * * * *means to execute a task every minute, and 30 9 * * 1-5means to execute a task at 9:30 every Monday to Friday.