Linux Shell Scripting Cookbook - Third Edition

How to do it...

A crontab entry specifies the time to execute a command and the command to be executed. Each line in the cron table defines a single command. The command can either be a script or a binary application. When cron runs a task, it runs as the user who created the entry, but it does not source the user's .bashrc. If the task requires environment variables, they must be defined in the crontab.

Each cron table line consists of six space-delimited fields in the following order:

• Minute (0 - 59)
• Hour (0 - 23)
• Day (1 - 31)
• Month (1 - 12)
• Weekday (0 - 6)
• COMMAND (the script or command to be executed at the specified time)

The first five fields specify the time when an instance of the command is to be executed. Multiple values are delimited ...