atrun runs jobs queued by
at(1). Root's
crontab(5) must contain the line:
*/10 * * * * root /usr/libexec/atrun
so that
atrun(8) gets called every ten minutes.
At every invocation, every job in lowercase queues whose starting time has passed is started. A maximum of one batch job (denoted by uppercase queues) is started each time
atrun is invoked.