The following snippet of code, which happily runs on both Windows and *NIX operating systems, was originally written as a wrapper for a backup process which lacked any email notification facilities - As such, there was no indication available for when the backup may have failed on a given occasion. This wrapper script runs around the (backup) process and captures all output sent to STDOUT/STDERR and sends the results to a specified email address.

In addition to being a very useful little piece of system administration code, this code also neatly demonstrates the namespace specification of localised variables (@output within the eval block) which may prove illustrative to some - This is also documented on the perlsub man page under the heading "Temporary Values via local()".

#!c:\Perl\Bin\Perl.exe

use constant EMAIL => 'you@yourdomain.com';
use constant SERVER => 'mail.yourdomain.com';

use IPC::Open3;
use Net::SMTP;
use strict;

my $cmd = join ' ', @ARGV;

my $mail = Net::SMTP->new( SERVER );

$mail->to( EMAIL );
$mail->mail( 'root@yourdomain.com' );
$mail->data();

my @output;
@output = eval {
    local *output;
    open3(
        "<&STDIN",
        \*OUTPUT,
        \*OUTPUT,
        $cmd
    ) || die $!;
    push @::output, $_ while (<OUTPUT>);
    close OUTPUT;
    return @::output;
};

if ($@) {
    $mail->datasend( "The command '$cmd' could not be executed - $@\n"
+ );
} else {
    $mail->datasend( join('', @output), "\n" );
}

$mail->dataend;
$mail->quit;
exit 0;

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In reply to Command Line Program Wrapper by rob_au

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