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

I am trying to run a remote command through a Perl script and then capturing that output to a file on the local system.

This is what I have so far(doesn't work): 

open (CSV, ">", $ADDListPresent) or die $!;
my @CreateList = ( '/usr/bin/sudo',
                   '-u', 'homer',
                   '/usr/bin/ssh', qq($HomerServer),
                   '/bin/ls',
                  );
system("$CreateList > data/test.txt");
close CSV;

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Re: Capturing remote command output to a file
by ikegami (Patriarch) on Aug 17, 2009 at 20:10 UTC

    It seems you were trying to use system safely by avoiding the shell by using it's multi-argument form, then abandoned your efforts and introducing other errors in the process. Solutions: 

    • # Not portable to Windows
sub shell_quote {
    my ($arg) = @_;
    $arg =~ s/'/'\\''/g;
    $arg = "'$arg'";
    return $arg;
}

my $cmd = join ' ', map shell_quote($_), @CreateList;
system("$cmd > data/test.txt") and die;

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    • open(my $fh_out, '>', 'data/test.txt') or die;
open(my $pipe, '|-', @CreateList) or die;
print $fh_out $_ while <$pipe>;

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    • use IPC::Open2 qw( open2 );
open(my $fh_out, '>', 'data/test.txt') or die;
my $pid = open2('>&'.fileno($fh_out), '<&STDIN', @CreateList);
waitpid($pid, 0);

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Re: Capturing remote command output to a file
by SuicideJunkie (Vicar) on Aug 17, 2009 at 19:49 UTC
    my @CreateList = ...and
    system("$CreateList > data/test.txt");

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    Involves two completely different variables, one an array and one a scalar. Did use strict not tell you about that problem?
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Re: Capturing remote command output to a file
by josh097 (Initiate) on Aug 17, 2009 at 20:18 UTC
    From what I have read system() only captures the exit code of what you are executing.
    Have you tried backticks (` ` - under the escape key)? Edit: Nvm, I re-read your code. Try: 
    system("$CreateList[0] $CreateList[1] $CreateList[2] $CreateList[3] $C
+reateList[4] > data/test.txt");

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      Duhhhh... Arrays have elements, who woulda thunk? ;-)

      Thanks josh097.

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Re: Capturing remote command output to a file
by BioLion (Curate) on Aug 18, 2009 at 08:39 UTC

    Capture::Tiny is also very handy for capturing output from system calls, I asked a similar question a while back and it was the best suggestion made to me then.

    Just a something something...
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