If you need to run a job once, at is the tool perfectly suited for this need.
The at tool requires some options to run a job at a given moment.
Without any parameters, at pops up the following error :
Garbled time
The job can be either specified from the at prompt or using the -f
Here is an example to run a job in a minute from the time the command at is executed :
at now + 1 minute
at>echo "This is a test"
at now + 1 minutes
at>echo "This is a test"
Using a text file :
at now + 1 minute -f job_file
Once the job is completed, an email is sent. Check your local Mailbox using the mail command.
Good tutorials around at providing additional examples :
https://www.computerhope.com/unix/uat.htm
https://tecadmin.net/one-time-task-scheduling-using-at-commad-in-linux/
https://linuxconfig.org/how-to-schedule-tasks-using-at-command-on-linux
https://www.thegeekstuff.com/2010/06/at-atq-atrm-batch-command-examples/