Comments on: Alarm clock: How To Set Timeout For A Shell Command

By: Bill

Bill — Tue, 12 Jul 2011 17:42:51 +0000

Thanks, that works great!

By: me

me — Sat, 12 Feb 2011 23:13:23 +0000

There is a command “timeout” in the latest Ubuntu Linux (10.10).

Example:
date; timeout 10m foo; date

By: Pedro

Pedro — Mon, 24 Jan 2011 04:12:19 +0000

God bless you!

By: Linus

Linus — Thu, 30 Sep 2010 16:23:44 +0000

$ sh foo & sleep 5 && kill $! & fg ### (note the last “&” is not “&&”, so you foreground the job immediately)

By: Fred

Fred — Wed, 25 Aug 2010 08:51:59 +0000

Great, thanks!

By: Chris

Chris — Fri, 22 Jan 2010 21:37:21 +0000

Thanks, the doalarm program worked very nicely for my purposes.

By: Cybergavin

Cybergavin — Tue, 17 Nov 2009 18:27:46 +0000

Thanks. Using the perl snippet is neat. Pretty much all UNIX systems come with bash and perl. So, this is cool.

By: Peter

Peter — Tue, 14 Jul 2009 06:22:21 +0000

hey, you’re right… that’s funny.
I tried to dig some deeper using strace and funnily it does not show up then:

strace perl -e “alarm shift @ARGV; exec @ARGV” 5 cat >/dev/null 2>&1

interesting issue, I do lack enough time to investigate
regards

By: Muhammad

Muhammad — Mon, 13 Jul 2009 14:01:13 +0000

Thanks Peter.

But the problem is appending >/dev/null 2>&1 to the command redirects stdout and stderr for the “command” not for the perl. So even by appending this to the command i still get “Alarm Clock” after command terminates.

For example perl -e ‘alarm shift @ARGV; exec @ARGV’ 5 foo arg1 arg2 > /dev/null 2>&1 ‘ will redirect output and stderr from ‘foo’ command not from the alarm command.
Thanks

By: Peter

Peter — Mon, 13 Jul 2009 10:59:51 +0000

Yup,
you can redirect the error output to stdout:
append ” >/dev/null 2>&1″ to the command

By: Muhammad

Muhammad — Tue, 07 Jul 2009 20:05:08 +0000

How can i suppress the stupid ‘alarm clock’ output when the timeout expires?
I’m running “perl -e ‘alarm shift @ARGV; exec @ARGV’ 5 cat” it terminates the cat command after 4 seconds but then i get stupid ‘Alarm clock’ output on the screen. I have to use this command in a shell script and i don’t want this output.

I have tried redirecting standard error and std out but if i specify >/dev/null at the end of cat command, it redirects ‘cat”s output not from perl -e….. Any ideas? Thanks a lot

By: Riccardo Murri

Riccardo Murri — Wed, 25 Feb 2009 14:15:56 +0000

Warning: the tip from Professor Fapsanders only works if “foo” does not require any input (background processes cannot do that).

For the general case, you need to background the alarm process instead, as the sample “timeout” script does.

By: Jadu Saikia

Jadu Saikia — Thu, 15 Jan 2009 10:16:11 +0000

Good one, I have to download and use it. Thanks.

The tip from Professor Fapsanders is also useful, we can make it more significant to kill the last background process by this:

$ sh foo & sleep 5 && kill $! && fg

// Jadu, unstableme.blogspot.com

By: Professor Fapsanders

Professor Fapsanders — Fri, 03 Oct 2008 17:37:05 +0000

You can also do it with bash using sleep and job control:
$ foo & sleep 10 && kill %1 && fg