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

Hello monks , how do i get the return value when I excute a shell command from a perl script. I am trying to do a remsh inside my perl script and I need to know the value key of the result , I mean 1 or 0 ,,, fail or secuss to remsh to that server. thanks

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Re: shell within perl
by rickest (Novice) on Aug 25, 2004 at 15:10 UTC
    see 'perldoc -f system'
Re: shell within perl
by bronto (Priest) on Aug 25, 2004 at 16:21 UTC

    The system function doc it contains some chunks of code that you could put directly into a subroutine:

    @args = ("command", "arg1", "arg2"); system(@args) == 0 or die "system @args failed: $?" You can check all the failure possibilities by inspecti +ng $? like this: if ($? == -1) { print "failed to execute: $!\n"; } elsif ($? & 127) { printf "child died with signal %d, %s coredump\ +n", ($? & 127), ($? & 128) ? 'with' : 'without +'; } else { printf "child exited with value %d\n", $? >> 8; }

    Update: I adapted it for a program of mine this way:

    #!/usr/bin/perl use strict ; use warnings ; use Carp ; # some code here sub check_cmd { my %parms = @_ ; croak "No commands" unless exists $parms{cmd} and ref($parms{cmd}) eq 'ARRAY' ; my @cmd = @{$parms{cmd}} ; $parms{onerror} = 'croak' unless exists $parms{onerror} ; $parms{onerror} = lc $parms{onerror} ; $parms{onerror} = 'croak' unless $parms{onerror} =~ /^(croak|carp|no +ne)$/ ; $parms{errormsg} = "@cmd failed" unless exists $parms{errormsg} ; my $result = system(@cmd) ; unless ($result == 0) { print STDERR $parms{errormsg} ; croak report_error($?,$!) if $parms{onerror} eq 'croak' ; if ($parms{onerror} eq 'carp') { carp report_error($?,$!) ; print STDERR "Press ENTER" ; scalar <STDIN> ; } } return $result >> 8 ; # exit value } sub report_error { my ($syserr,$message) = @_ ; my $signal = $syserr & 127 ; my $exitvalue = $syserr >> 8 ; my $error ; if ($syserr == -1) { $error = "failed to execute: $message" ; } elsif ($signal) { $error = "program died with signal $signal" ; } return $error ; }

    The subroutine was called like this:

    $ret = check_cmd(cmd => [$config{cvs_command},'login'], onerror => 'none', errormsg => "cvs login failed") ; unless ($ret == 0) { # do something... }

    I hope this helps a bit

    Ciao!
    --bronto


    The very nature of Perl to be like natural language--inconsistant and full of dwim and special cases--makes it impossible to know it all without simply memorizing the documentation (which is not complete or totally correct anyway).
    --John M. Dlugosz
Re: shell within perl
by jaco (Pilgrim) on Aug 25, 2004 at 16:25 UTC
    my ($sig, $ret) = ($?&255, $?>>8); die "child died from signal $sig" if $sig; die "child exited with code $ret" if $ret;