Difference between nohup vs at now
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26-06-2021 - |
Question
It seems that there is no difference between nohup and at now, but maybe there are subtleties?
Solution
The difference is that now
runs a command that can respond to HUP
signal, where as the nohup
runs a command that is immune to HUP
signal.
OTHER TIPS
Ed Heal is right. But another difference is that something run by nohup
still has a controlling terminal, whereas something run by at now
does not.
In addition to that, backgrounding something with nohup
causes it to run immediately, whereas at now
simply queues something to be run the next time atrun(8)
runs. In BSD unix, (FreeBSD/OpenBSD) at jobs are launched by atrun
which is launched periodically by cron
(or launchd
in OSX). In Linux, at jobs are run by at's own daemon, atd
, which by default launches jobs every 60 seconds.
Other flavours of unix may have different strategies, but in most cases you'll probably find that jobs launched by at now
are less immediate than jobs launched using nohup
.
nohup tells the system to continue running even after you log out. at is used to execute a command or multiple commands once at some future time.