Hi,

I am after some help with using PERL modules. 

I am trying to read options using the Getopt:Long module as follows;

#!/usr/bin/perl 

# import module
use Getopt::Long; 

# set default value for option
$debug = 0; 

# get value of debug flag
$result = GetOptions ("debug" => $debug);   

# print value
print "Debug flag is $debug";

However when I call this programme 
./script.pl
gives
Debug flag is 0
./script.pl --debug
gives
Debug flag is 0

The module seems to exist. If I try use Getopt::Long1; instead I get a
message that Getopt/Long1.pm doesn't exist and gives me the search
path as well. I can see Getopt/Long.pm module is in the search path
and it has the GetOptions subprogramme.

If I do 
perl ./script.pl -w --debug 
I get 
Name "main::result" used only once:possible typo at script.pl line 7.
Where $result = GetOptions ... is line 7.

What am I doing wrong?

Thanks,

Mick

Hi Mick

This had me stumped for a little while too until I noticed you had
made a minor typo by missing off a \.

The line: $result = GetOptions ("debug" => $debug);

should read:

$result = GetOptions ("debug" => \$debug);

Let me know if this solves your problem.

A couple of useful pages on this module are here:
http://perl.active-venture.com/lib/Getopt/Long.html
http://www.devshed.com/c/a/Perl/Processing-Command-Line-Options-with-PERL/0/

Note - on this second article the \'s are also all missing (I guess
this is due to the way the HTML is presented).

---

Request for Answer Clarification by mickr-ga on 23 Jul 2004 06:23 PDT

Hi Palitoy,

That worked as usual.

Another question $30 tip, if you choose to answer.

I want to pass filenames to a perl script, number of input files
unknown, output file one. Can you give me some examples, maybe the
following:

a) using ARGV where the command line might look like 
  script.pl infile1 infile2 ... infile5 outfile

b) using the getopt::long module where the command line might look like 
  script.pl -in=infile1 -in=infile2 ... -in=infile5 -out=outfile

c) any other better way of doing this.

Thanks,

Mick

---

Clarification of Answer by palitoy-ga on 23 Jul 2004 06:52 PDT

Hello Mick

Is this the kind of thing you require:

# BEGIN #

#!/usr/bin/perl
# import module
use Getopt::Long;

# read options
$result = GetOptions ("i=s" => \@list, "o=s" => \$output);

# save the file using the $output name
open(FILE, ">$output.txt");
foreach $input_value (@list) {
  print FILE "$input_value\n";
}
close (FILE);

# END #

Syntax:
scriptname.pl --i=hello --i=goodbye --o=outputfilename

This would then produce a file called outputfilename.txt with "hello"
on line 1 and "goodbye" on line 2.

Let me know if this is correct and whether you need any more examples.

---

Clarification of Answer by palitoy-ga on 23 Jul 2004 06:58 PDT

I forgot to add the ARGV version:

# BEGIN #

#!/usr/bin/perl

# process the command line and save it to a file with a filename of the
# last argument on the command line
open(FILE, ">$ARGV[$#ARGV].txt");
foreach $argnum (0 .. $#ARGV-1) {
  print FILE "$ARGV[$argnum]\n";
}
close (FILE);

# END #

Syntax:
scriptname.pl hello goodbye outputfilename

This would then produce a file called outputfilename.txt with "hello"
on line 1 and "goodbye" on line 2.

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Clarification of Answer by palitoy-ga on 23 Jul 2004 06:59 PDT

Thanks for the generous tip and 5-star rating, both are very much appreciated.

Thanks, I am a happy customer as usuall.