script doesn't print anything

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

Hello monks!

As some of you may be aware I have bee struggling with a perl script for a few days in my attempts to parse the extremely verbose output of 3par commands.

I feel I am inching closer to my goal, but I have hit a new stumbling block. For some reason this script does not output anything at all, even tho it is loaded with test print statements.

#!/usr/bin/perl
use strict;
use warnings;
use IO::Pipe;
use IO::Handle; 


my @systems = ('3par-S400','3par-E200');
my $system;
my $output;
my $command;

STDOUT->autoflush(1);
print "this is test statement one!\n";

foreach $system (@systems) { 

    $output = run_command($system);

    STDOUT->autoflush(1);
    print "this test is just before the while loop!\n";

    while (<$output>) {
        next if (m/^$/);
        last if (m/^Press.*/);
        my (@headers) = /\d\d:\d\d:\d\d/;
        STDOUT->autoflush(1);
        print "This is a test before the loop from insde while!\n";
        foreach my $header(@headers) {
        STDOUT->autoflush(1);
        print "this is a test\n";
        STDOUT->autoflush(1);
        print "$header \n";
        }
        
 }

    close($output);

}


sub run_command {

my $user = 'gmon';
my $system = shift;
my $protocol = 'ssh';
my $command = "statvv -ni";
my $space = " ";
#The following is bad but it works for now..
my $do_command = $protocol . $space . "-l $user" . $space . $system . 
+$space . $command; 
my $cmd = new IO::Pipe;
$cmd->reader($do_command);
return $cmd;
   
    
}
[download]

It doesn't even print any errors. Any thoughts? Thanks Monks!

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Re: script doesn't print anything by zentara (Cardinal) on Aug 24, 2010 at 18:29 UTC
It doesn't even print any errors. Any thoughts? I'm not sure why you chose IO::Pipe to run this, but the IO::Pipe docs show `$pipe->reader(qw(ls -l)); while(<$pipe>) { print ... }` [download] I would think that IPC::Open3 would be more straightforward. Like this example which shows how to grab STDERR too. #!/usr/bin/perl use warnings; use strict; use IPC::Open3; use IO::Select; my $pid = open3(\WRITE, \READ,\ERROR,"/bin/bash"); my $sel = new IO::Select(); $sel->add(\READ); $sel->add(\ERROR); my($error,$answer)=('',''); while(1){ print "Enter command\n"; chomp(my $query = <STDIN>); #send query to bash print WRITE "$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. [download] I'm not really a human, but I play one on earth. Old Perl Programmer Haiku flash japh	[reply] [d/l] [select]

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Re: script doesn't print anything
by zentara (Cardinal) on Aug 24, 2010 at 18:29 UTC

It doesn't even print any errors. Any thoughts?

I'm not sure why you chose IO::Pipe to run this, but the IO::Pipe docs show

$pipe->reader(qw(ls -l));
 while(<$pipe>) {
                 print   ...
               }
[download]

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

my $pid = open3(\*WRITE, \*READ,\*ERROR,"/bin/bash");

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

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

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

while(1){

 print "Enter command\n";
 chomp(my $query = <STDIN>);
 
 #send query to bash
 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.
[download]

I'm not really a human, but I play one on earth.
Old Perl Programmer Haiku flash japh

[reply]
[d/l]
[select]