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

I'm writing a script to act as a ssh wrapper and I want to have to option of using a config file when offered the command line argument of "--config". According ot the perldoc documentation, using "config" => /$config should set $config to 0, initializing it. Unfortunately, it seems to not get the value assigned to it.

this is the output of the program 

./strew.pl --help
Use of uninitialized value in concatenation (.) or string at ./strew.p
+l line 65.
config: ""

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Below is code from where I'm dealing w/ command line args. 

use Getopt::Long;
use Config::Auto;
#use Data::Dumper;

my @servers         = ();
my @commands     = ();
my @files         = ();
my $user         = $ENV{USER};
my $file             = ();
my $dest         = ();
my $help         = ();
my $config        = () ;
GetOptions ("user=s" => \$user, "server=s" => \@servers, "command=s" =
+> \@commands, "file=s" =>\$file, "dest=s"=> \$dest, "config" => \$con
+fig, "help" => \$help);

print "config: \"$config\"\n";

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Thanks!!,
Nick

Replies are listed 'Best First'.
Re: Problem with GetOpts::Long
by Mr. Muskrat (Canon) on Mar 21, 2003 at 23:00 UTC

    Instead of using my $config = (); try my $config = 0;. It makes a big difference.

    use Getopt::Long;
use Config::Auto;
#use Data::Dumper;

my @servers      = ();
my @commands     = ();
my @files        = ();
my $user         = $ENV{USER};
my $file         = ();
my $dest         = ();
my $help         = ();
my $config       = 0;  # 0 not ()
GetOptions ("user=s" => \$user, "server=s" => \@servers, "command=s" =
+> \@commands, "file=s" =>\$fil
+e, "dest=s"=> \$dest, "config" => \$config, "help" => \$help);
print "config: \"$config\"\n";

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    Now if you run it with the --config option, it's set to 1 otherwise it's 0.

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      ./strew.pl --config
config: "0"

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      -----
      I went ahead and did what you reccomended, changing it from = () to = 0;
      It seems to be keeping whatever I set it to, instead of changing it's value.
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[d/l]

        Something else is wrong then, I copied the code you have here, changed the default assignment, and it works for me.

        [jason@traveller jason]$ ./test.pl 
config: "0"
[jason@traveller jason]$ ./test.pl --config
config: "1"

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        We're not surrounded, we're in a target-rich environment!
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[d/l]
        Right. Bug. The part (above) that says 
          "config" => \$config,

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        should actually be 
          "config!" => \$config,

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        to indicate that the --config option is to be a boolean flag type of value.

        jdporter
        The 6th Rule of Perl Club is -- There is no Rule #6.

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Re: Problem with GetOpts::Long
by jasonk (Parson) on Mar 21, 2003 at 23:03 UTC

    Actually the documentation says that arguments which are not specified on the command line are ignored, so if you want it to have a default you need to set that default yourself before calling GetOptions. Simply replacing my $config = (); with my $config = 0; will make it work the way you want.

    We're not surrounded, we're in a target-rich environment!
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