Linux task scheduling crontab command (periodic execution command/script)

grammar

crontab [ -u user ] {
    
     -l | -r | -e }

This is man help (checked under Xshell, not directly using cloud server)

-u means the specified user, execute the task as the user, if not added, the current user will be the default
-l means to list the current task list
-e means to edit the task (script) to be executed
-r to terminate the task scheduling

The format of editing content is as follows: program can be a command or a shell script