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Top Forums Shell Programming and Scripting Interpreting arguments in Perl program. Post 302716451 by D2K on Tuesday 16th of October 2012 11:49:25 AM
Old 10-16-2012
Interpreting arguments in Perl program.

Hello.
I'm new to Perl and I am not sure how to interpret command line arguments in the program. I am writing a program similar to the Unix utility 'tail' and need to check if first argument is '-1' ([dash]1) or any arbitrary number of lines to output. How would I write an 'if' statement to check for the dash (-) and a number? Checking for the dash is trivial below.
Code:
if ($ARGV[0] eq "-")
{
    print "I think it works\n";
}

How can I parse the dash with a number attached? Any numerical value?

Sample program run below:

File 'samp.txt' contains:
Hello World
This
Is
A
Test

-------
$tail.pl -3 samp.txt
Is
A
Test
 

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Perl::Critic::Policy::Subroutines::ProhibitManyArgs(3pm)User Contributed Perl DocumentatioPerl::Critic::Policy::Subroutines::ProhibitManyArgs(3pm)

NAME
Perl::Critic::Policy::Subroutines::ProhibitManyArgs - Too many arguments. AFFILIATION
This Policy is part of the core Perl::Critic distribution. DESCRIPTION
Subroutines that expect large numbers of arguments are hard to use because programmers routinely have to look at documentation to remember the order of those arguments. Many arguments is often a sign that a subroutine should be refactored or that an object should be passed to the routine. CONFIGURATION
By default, this policy allows up to 5 arguments without warning. To change this threshold, put entries in a .perlcriticrc file like this: [Subroutines::ProhibitManyArgs] max_arguments = 6 CAVEATS
PPI doesn't currently detect anonymous subroutines, so we don't check those. This should just work when PPI gains that feature. We don't check for @ARG, the alias for @_ from English.pm. That's deprecated anyway. TO DO
Don't include $self and $class in the count. CREDITS
Initial development of this policy was supported by a grant from the Perl Foundation. AUTHOR
Chris Dolan <cdolan@cpan.org> COPYRIGHT
Copyright (c) 2007-2011 Chris Dolan. Many rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. The full text of this license can be found in the LICENSE file included with this module perl v5.14.2 2012-06-07 Perl::Critic::Policy::Subroutines::ProhibitManyArgs(3pm)
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