at

The at command line tool is used to schedule commands or scripts to be executed at a specific time. It allows you to specify a time and date for a command to run only once. The syntax for using at is as follows:

at <time> [date]

Here, <time> represents the time of execution in 24-hour format (HH:MM), and [date] is an optional parameter that specifies the date. If the [date] parameter is omitted, the command is scheduled to run on the current day.

Once the at command is invoked, it opens an interactive shell where you can enter the command(s) to be executed. The commands can be shell commands, shell scripts, or any executable files. Pressing Ctrl+D or typing EOF terminates the input.

Once the command is scheduled, it is stored in the at queue and executed automatically at the specified time. The output of the scheduled command is sent via email to the user who scheduled the command.

You can list the scheduled tasks using the atq command and remove a scheduled task using the atrm command, followed by the job number.

The at command is useful when you want to automate tasks at specific times, such as running backups, generating reports, or performing routine maintenance tasks.