Suppressing console output

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

Replies are listed 'Best First'.
Re: Suppressing console output by blazar (Canon) on Sep 16, 2005 at 09:27 UTC
How are you "calling" A? You can use `qx` aka backticks and just discard the output. Or else, following your logic, you can just re-open STDOUT to where you like most, e.g. an "in-memory" file (see open) or to a suitable actual file, including say `/dev/null` (assuming you're on *NIX).	[reply] [d/l] [select]
Re^2: Suppressing console output by loris (Hermit) on Sep 16, 2005 at 10:19 UTC
Hello blazar, Sorry for being so vague. I am using `system`. However, your suggestion about "in-memory" files was just what I was looking for. Thanks, loris	[reply] [d/l]
Re: Suppressing console output by svenXY (Deacon) on Sep 16, 2005 at 09:33 UTC
Hi, it looks like you need to partly rewrite Script A anyway, so why don't you just add a parameter like --verbose and only output if the script has been called with that parameter? Read more... (663 Bytes) Alternatively, you could use something like Log::Log4perl and then add a parameter which sets the loglevel to FATAL if you don't want output. Regards, svenXY	[reply] [d/l] [select]
Re^2: Suppressing console output by loris (Hermit) on Sep 16, 2005 at 09:41 UTC
Hello svenXY, You're right, I could do this, but I'm feeling lazy and don't want to change every line with a `print`. I'd like to somehow switch the output off globally. The idead of using Log::Log4perl is good, although as my scripts are quite short, it could be overkill. Thanks, loris	[reply] [d/l]
Re: Suppressing console output by zentara (Cardinal) on Sep 16, 2005 at 14:22 UTC
There are some shell syntax tricks you can try to suppress output, but the results vary from script to script. `$r = system( "scriptA @options >/dev/null 2>&1 ");` [download] I'm not really a human, but I play one on earth. flash japh	[reply] [d/l]
Re: Suppressing console output by Lunchy (Sexton) on Sep 16, 2005 at 18:08 UTC
If I understand what you want do to correctly, whenever I want to do this, I just redirect the STDOUT filehandle to one of my own by assigning STDOUT's glob to a different one, this can be done like this... `my $mySTDOUT = (); my $oldSTDOUT = (); oldSTDOUT = STDOUT; STDOUT = mySTDOUT; my $test = 'this is a test'; print "$test\n";` [download] After you run this, you should get NO output from that print command. So you'd want do to this in script A. Then, if you ever wanna restore STDOUT so you see it's output again, you can do this... `STDOUT = oldSTDOUT;` [download] Hope that helps. -Lunchy	[reply] [d/l] [select]
Re^2: Suppressing console output by Tanktalus (Canon) on Sep 16, 2005 at 19:30 UTC
The faster/easier way to do that is: `{ local STDOUT; open STDOUT, '>/dev/null'; # do stuff that may print out. }` [download] Note also that you're creating $mySTDOUT and $oldSTDOUT and not actually using them anywhere. $mySTDOUT is not the same thing as mySTDOUT!	[reply] [d/l]
Re^3: Suppressing console output by Lunchy (Sexton) on Sep 16, 2005 at 20:02 UTC
I knew that $mySTDOUT isnt' the same as mySTDOUT, but I thought I needed to create something with a 'mySTDOUT' name to keep strict from barking about mySTDOUT, but it turns it I didn't need to. :) As far as not using oldSTDOUT. You'll note I mentioned that he could use oldSTDOUT to restore STDOUT to normal later on if he wanted to. Perhaps there's another way to do this, but if so I don't know what it is. :) By the way, I DO like your solution and will try to remember it for the next time I need to do this, however, it does assume one is on an OS that has a /dev/null. :) Cheers! -Lunchy	[reply]