Re^5: How to stop printing the output of a command on screen when the command fails?

You probably want to use IO::Select with the IPC3 filehandles, so you won't block. Look at this example, using the calculator program, bc. You can adapt your p4 to run this way.

#!/usr/bin/perl
use warnings;
use strict;
use IPC::Open3;
use IO::Select;

#interface to "bc" calculator
my $pid = open3(\*WRITE, \*READ,\*ERROR,"bc");

my $sel = new IO::Select();

$sel->add(\*READ);
$sel->add(\*ERROR);

my($error,$answer)=('','');

while(1){

 print "Enter expression for bc, i.e. 2 + 2\n";
 chomp(my $query = <STDIN>);
 
 #send query to bc
 print WRITE "$query\n";

 foreach my $h ($sel->can_read)
 {
   my $buf = '';
   if ($h eq \*ERROR)
   {
     sysread(ERROR,$buf,4096);
     if($buf){print "ERROR-> $buf\n"}
   }
   else
   {
     sysread(READ,$buf,4096);
     if($buf){print "$query = $buf\n"}
   }
 }
}

waitpid($pid, 1);
# It is important to waitpid on your child process,  
# otherwise zombies could be created.
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I'm not really a human, but I play one on earth.
Old Perl Programmer Haiku ................... flash japh

Comment on Re^5: How to stop printing the output of a command on screen when the command fails? Download Code

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Re^6: How to stop printing the output of a command on screen when the command fails? by perl_mystery (Beadle) on Dec 24, 2010 at 18:38 UTC
I really need help on this.Tried in a different way as below,am not able to store the STDERR output into any variable.The below program doesnt print anything.I have been working on this since last night,couldnt get a handle on this.Any help is truly appreciated. #!/usr/bin/perl -w use strict; use warnings; use diagnostics; #use diagnostics; use IPC::Open3; my @changed_paths; my @changed_files=("//depot/perl/tools/scripts/files/data.c"); foreach my $file (@changed_files) { my($wtr, $rdr, $err); use Symbol 'gensym'; $err = gensym; my $pid = open3($wtr, $rdr, $err,'p4 where $file'); print "$err\n"; #prints as GLOB(0x183f108),why is it so? #waitpid( $pid, 0 ); //Why do we need this?Program never halts if th +is is present my $child_exit_status = $? >> 8; if ($err eq 'file(s) not in client view') { push @changed_paths,$file; } print @changed_paths; } [download]	[reply] [d/l]
Re^7: How to stop printing the output of a command on screen when the command fails? by RedElk (Hermit) on Dec 24, 2010 at 22:55 UTC
The single quotes in line 13 of your posted code. Is that really what you want - not interpolated? Perldoc shows it differently.	[reply]
Re^7: How to stop printing the output of a command on screen when the command fails? by ikegami (Patriarch) on Dec 24, 2010 at 22:38 UTC
It doesn't matter how many different tools you use to capture STDERR, it won't help you when the program doesn't write the error message you are trying to capture to STDERR. See Re^3: How to stop printing the output of a command on screen when the command fails?.	[reply]
Re^8: How to stop printing the output of a command on screen when the command fails? by perl_mystery (Beadle) on Dec 25, 2010 at 01:48 UTC
What's confusing me is,if I run the below command from command prompt I see stderr getting supressed but where as when I run it in perl using backticks it fails,what could be going wrong> `>p4 where //depot/perl/tools/files/data.c > NUL: 2>&1` [download]	[reply] [d/l]
Re^9: How to stop printing the output of a command on screen when the command fails? by ikegami (Patriarch) on Dec 28, 2010 at 22:49 UTC
Re^6: How to stop printing the output of a command on screen when the command fails? by perl_mystery (Beadle) on Dec 24, 2010 at 18:42 UTC
Erasing this,posted twice	[reply]