CODEWITHSUNDEEP
perlfilehandle
PPP
PPP

Reputation: 359

Perl: How to run more than 1 command inside open while opening a filehandle into commands

How to run more than 1 command inside open?

I have a code below. Here, I am running make $i inside open, but now I want to run more than 1 command here, say make $i; sleep 30; echo abc. How can I do that?

foreach $i (@testCases) {
   my $filehandle;
   if ( ! (my $pid = open( $filehandle, "make $i 2>&1 |" ) )) {
       die( "Failed to start process: $!" );
   }
   else {
       print "Test started\n";
   }
}

Just to add the following is not working properly:

if (!($pid = open( my $pipe, "make $i; sleep 30; echo abc |" ))) " {
  print "Problem in openeing a filehandle\n";
} else {
     print "$pid is pid\n";
     my $detailedPs=`tasklist | grep "$pid"`;
     chomp ($detailedPs);
     print "$detailedPs is detailedPs\n";
 }

Here, I am getting $detailedPs as empty. If things would have run correctly, I would have got something in $detailedPs

Upvotes: 2

Views: 201

Answers (1)

ikegami
ikegami

Reputation: 385506

open( my $pipe, "make $i; sleep 30; echo abc |" )
   or die( "Can't launch shell: $!\n" );

my $stdout = join "", <$pipe>;  # Or whatever.

close( $pipe )
   or die( "A problem occurred running the command.\n" );

Preferred:

open( my $pipe, "-|", "make $i; sleep 30; echo abc" )

Short for: (non-Windows)

open( my $pipe, "-|", "/bin/sh", "-c", "make $i; sleep 30; echo abc" )

But note that you have a code injection bug. Fixed:

open( my $pipe, "-|", "/bin/sh", "-c", 'make "$1"; sleep 30; echo abc', "dummy", $i )

With IPC::Run:

use IPC::Run qw( run );

run(
   [ "/bin/sh", "-c", 'make "$1"; sleep 30; echo abc', "dummy", $i ],
   '>', \my $stdout  # Or whatever.
)
   or die( "A problem occurred running the command.\n" );

But you'd be better off avoiding a shell.

use IPC::Run qw( run );

run(
   [ 'make', $i ],
   '|', [ 'sleep', '30' ],
   '|', [ 'echo', 'abc' ],
   '>', \my $stdout
)
   or die( "A problem occurred running the command.\n" );

Upvotes: 2

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