To schedule a task using cron, you need to edit a special file called the crontab file in a text editor and add your task in it, in a particular format. Then, cron will run the task for you at the time you specify in the crontab file. You can specify any intervals of time, from seconds to weeks and even years!

When it is appropriate to schedule a process using AT command?

The at command is used to schedule a command to run one time. TIME is a very flexible specification of when the command should run. See the text book for examples. at then reads from standard input for list of commands to run at this time.

Which scheduler is used in Linux?

Linux uses a Completely Fair Scheduling (CFS) algorithm, which is an implementation of weighted fair queueing (WFQ). Imagine a single CPU system to start with: CFS time-slices the CPU among running threads. There is a fixed time interval during which each thread in the system must run at least once.