38.18 nohupWhen UNIX first started, even local terminals very often communicated with the system via short-haul modems. (After all, UNIX was invented by the phone company.) When someone logged out, the modem hung up the phone - and conversely, if the modem hung up, a "hangup" signal was sent to the login shell, whereupon it terminated, bringing down all its child processes ( 38.3 ) with it. In the C shell, processes that you run in the background are immune to hangups, but in the Bourne shell, a process that you started in the background might be abruptly terminated.
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Any output from Of course, if you want to run jobs at off hours, you might do even better using at , cron , or batch ( 40.1 ) . nohup is sometimes handy in shell scripts to make them ignore the HUP and TERM signals ( 38.8 ) , though trap ( 44.12 ) is more versatile. (In System V, nohup causes a command to ignore HUP and QUIT, but not TERM.) - |
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