Nohup - Revision history

Jimbo: rollback prior to mistaken "&" edit

2007-09-17T18:06:26Z

rollback prior to mistaken "&" edit

65.9.250.68 at 17:03, 17 September 2007

2007-09-17T17:03:23Z

65.9.250.68 at 17:03, 17 September 2007

2007-09-17T17:03:12Z

68.178.61.59 at 16:37, 17 September 2007

2007-09-17T16:37:55Z

68.178.61.59 at 16:37, 17 September 2007

2007-09-17T16:37:26Z

Dave: info and comparisson w/ GNU screen util

2006-09-09T02:16:58Z

info and comparisson w/ GNU screen util

Jimbo at 21:21, 8 September 2006

2006-09-08T21:21:42Z

New page

'''nohup''' is a godsend for those of us who spend lots of time shelling into remote machines. You can invoke any other command with '''nohup''', like the following:

ph34r# '''nohup find / -name "*a*" > /home/jimbo/dumbfindcommand.out'''

And what happens is, your command gets executed but told to ignore all SIGHUP signals. The net impact is, you can now close your shell session, and still have your command continue to run - whereas normally, as soon as your shell died - either due to you closing it or to the vagaries of the internet closing it for you - all processes you had running would immediately die as well.

The example given above - give me a listing of every single file on my entire server which contains the letter "a" in its name - would obviously take an absurdly long time to run. If you had to accomplish a task like this on a machine hundreds of miles away, it would be nearly impossible without finding some way of detaching it from your shell session. You could also use the [[at]] scheduler, but that can be a real pain because it only fires off every 5 minutes (by default), and you hate to just set something up and walk away without checking to see that it fired up and began doing what it was supposed to. With '''nohup''', you can just fire it up immediately, use a [[ps]] or other command to monitor that it is running and appears to be doing what it ought to be doing, and then quit worrying about it 'til it's done.

[[Category : System Commands]]

← Older revision		Revision as of 18:06, 17 September 2007
Line 9:		Line 9:
	Another alternative is the GNU [[screen]] utility, but that would be geared more towards people who want to attach and detach from shell sessions, not just folks who want a job running in the background to stay alive when not connected.		Another alternative is the GNU [[screen]] utility, but that would be geared more towards people who want to attach and detach from shell sessions, not just folks who want a job running in the background to stay alive when not connected.

−	~~Yet one more choice would be to add & to the end of your command. For example:~~
−
−	~~ph34r#find / -name "a" > /home/jimbo/dumbfindcommand.out&'''~~
−
−	~~This will run it as a seperate process and will let you know what the process number is when started, and when it ends.~~
−
−	~~Shown when started~~
−	~~[1] 90557~~
−
−	~~Shown when ended~~
−	~~[1] Done find / -name "a" > /home/jimbo/dumbfindcommand.out&'''~~
	[[Category : System Commands]]		[[Category : System Commands]]

@@ Line 17: / Line 17: @@
   Shown when started
   [1] 90557
-−
   Shown when ended
   [1]    Done                          find / -name "*a*" > /home/jimbo/dumbfindcommand.out&'''
 [[Category : System Commands]]

@@ Line 11: / Line 11: @@
 Yet one more choice would be to add & to the end of your command. For example:
-ph34r#find / -name "*a*" > /home/jimbo/dumbfindcommand.out&'''
+ ph34r#find / -name "*a*" > /home/jimbo/dumbfindcommand.out&'''
 This will run it as a seperate process and will let you know what the process number is when started, and when it ends.
-Shown when started
+ Shown when started
-[1] 90557
+ [1] 90557
-−
-Shown when ended
+ Shown when ended
-[1]    Done                          find / -name "*a*" > /home/jimbo/dumbfindcommand.out&'''
+ [1]    Done                          find / -name "*a*" > /home/jimbo/dumbfindcommand.out&'''
 [[Category : System Commands]]

@@ Line 19: / Line 19: @@
 Shown when ended
-[1]    Done                          ls -G -R bsdadmin/
+[1]    Done                          find / -name "*a*" > /home/jimbo/dumbfindcommand.out&'''
 [[Category : System Commands]]

← Older revision		Revision as of 16:37, 17 September 2007
Line 9:		Line 9:
	Another alternative is the GNU [[screen]] utility, but that would be geared more towards people who want to attach and detach from shell sessions, not just folks who want a job running in the background to stay alive when not connected.		Another alternative is the GNU [[screen]] utility, but that would be geared more towards people who want to attach and detach from shell sessions, not just folks who want a job running in the background to stay alive when not connected.

		+	Yet one more choice would be to add & to the end of your command. For example:
		+
		+	ph34r#find / -name "a" > /home/jimbo/dumbfindcommand.out&'''
		+
		+	This will run it as a seperate process and will let you know what the process number is when started, and when it ends.
		+
		+	Shown when started
		+	[1] 90557
		+
		+	Shown when ended
		+	[1] Done ls -G -R bsdadmin/
	[[Category : System Commands]]		[[Category : System Commands]]

← Older revision		Revision as of 02:16, 9 September 2006
Line 6:		Line 6:

	The example given above - give me a listing of every single file on my entire server which contains the letter "a" in its name - would obviously take an absurdly long time to run. If you had to accomplish a task like this on a machine hundreds of miles away, it would be nearly impossible without finding some way of detaching it from your shell session. You could also use the [[at]] scheduler, but that can be a real pain because it only fires off every 5 minutes (by default), and you hate to just set something up and walk away without checking to see that it fired up and began doing what it was supposed to. With '''nohup''', you can just fire it up immediately, use a [[ps]] or other command to monitor that it is running and appears to be doing what it ought to be doing, and then quit worrying about it 'til it's done.		The example given above - give me a listing of every single file on my entire server which contains the letter "a" in its name - would obviously take an absurdly long time to run. If you had to accomplish a task like this on a machine hundreds of miles away, it would be nearly impossible without finding some way of detaching it from your shell session. You could also use the [[at]] scheduler, but that can be a real pain because it only fires off every 5 minutes (by default), and you hate to just set something up and walk away without checking to see that it fired up and began doing what it was supposed to. With '''nohup''', you can just fire it up immediately, use a [[ps]] or other command to monitor that it is running and appears to be doing what it ought to be doing, and then quit worrying about it 'til it's done.
		+
		+	Another alternative is the GNU [[screen]] utility, but that would be geared more towards people who want to attach and detach from shell sessions, not just folks who want a job running in the background to stay alive when not connected.

	[[Category : System Commands]]		[[Category : System Commands]]