Disable output from system

ewhitt has asked for the wisdom of the Perl Monks concerning the following question:

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Re: Disable output from system by Anonymous Monk on Mar 26, 2009 at 04:42 UTC
Don't ask for output :) `\| \| V system('tar -vxf upload.tar'); ^ \| \|` [download]	[reply] [d/l]
Re: Disable output from system by targetsmart (Curate) on Mar 26, 2009 at 04:32 UTC
On unix system using bash(shell), one way of suppressing error and output `tar -vxf upload.tar 2>&1 >/dev/null` [download] Vivek -- In accordance with the prarabdha of each, the One whose function it is to ordain makes each to act. What will not happen will never happen, whatever effort one may put forth. And what will happen will not fail to happen, however much one may seek to prevent it. This is certain. The part of wisdom therefore is to stay quiet.	[reply] [d/l]
Re^2: Disable output from system by rovf (Priest) on Mar 26, 2009 at 08:55 UTC
I think you mean: `tar -vxf upload.tar >/dev/null 2>&1` [download] -- Ronald Fischer <ynnor@mm.st>	[reply] [d/l]
Re: Disable output from system by rovf (Priest) on Mar 26, 2009 at 08:54 UTC
In addition to what already has been said, here other variations: `qx(tar ...); # Burns more CPU cycles, but who cares ;-) use File::Spec::Functions qw(devnull); system('tar .... >'.devnull.' 1>&2'); # works on *nix and windoze` [download] -- Ronald Fischer <ynnor@mm.st>	[reply] [d/l]
Re^2: Disable output from system by Anonymous Monk on Mar 26, 2009 at 10:57 UTC
Hi, Roland. You wrote: system('tar .... >'.devnull.' 1>&2'); # works on *nix and windoze As I can see you redirect STDOUT to devnull and then again you redirect STDOUT to STDERR... Is this correct? I think it is typo, isn't it?	[reply]
Re^3: Disable output from system by rovf (Priest) on Mar 26, 2009 at 13:43 UTC
you redirect STDOUT to devnull and then again you redirect STDOUT to STDERR... Is this correct? Sorry, a typo indeed. Of course you have to do something like `'....>'.devnull.' 2>&1'` [download] and not "1>&2". I mistakingly exchanged 2 and 1. My point was that you have to redirect first to devnull, and then do the 2>&1, not the other way around. -- Ronald Fischer <ynnor@mm.st>	[reply] [d/l]
Re^2: Disable output from system by Tumata (Initiate) on Mar 26, 2009 at 10:59 UTC
Hi, Roland. You wrote: system('tar .... >'.devnull.' 1>&2'); # works on *nix and windoze As I can see you redirect STDOUT to devnull and then again you redirect STDOUT to STDERR... Is this correct? I think it is typo, isn't it ?	[reply]
Re: Disable output from system by educated_foo (Vicar) on Mar 26, 2009 at 22:04 UTC
You can dup stdout and stderr, then close them: `sub stfu_system { local (OUT, ERR); open OUT, ">&STDOUT"; open ERR, ">&STDERR"; close STDOUT; close STDERR; system @_; open STDOUT, ">&OUT"; open STDERR, ">&ERR"; }` [download]	[reply] [d/l]
Re^2: Disable output from system by ig (Vicar) on Mar 28, 2009 at 21:15 UTC
This will work for many commands but some will fail if they don't have STDOUT and/or STDERR open.	[reply]
Re^3: Disable output from system by educated_foo (Vicar) on Mar 28, 2009 at 22:30 UTC
True. For those (poorly-written) commands, `s!close\s+(\w+)!open $1, '>/dev/null'!`	[reply] [d/l]