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Full Discussion: Loops
Top Forums Shell Programming and Scripting Loops Post 302559345 by Chubler_XL on Monday 26th of September 2011 10:38:18 PM
Old 09-26-2011
opt 2>/dev/null this is just redirecting anything output to stderr (typically getopts will print some sort of message about illegal options eg "getopts: -i option unknown" to sterr). For example:
Code:
$ cat opt_eg
getopts p: opt 
echo opt is $opt
getopts p: opt 2> /dev/null
echo opt is still $opt
 
$ ./opt_eg -j
./opt_eg: illegal option -- j
opt is ?
opt is still ?

This program just throws away the error message from getopts and calls showUsage instead. There is a good chance that showUsage is an internal function to this script.

getopts sets $opt to ? if an invalid arugment is detected, the *) clause of the case statement picks up any value not matched by the other case clauses so it grabs ?, or any other value not listed above and calls showUsage.

The assumption is that showUsage would then exit (probably with some non-zero exit code) otherwise you will get usage output listed for every invalid option passed to the script.
Last edited by Chubler_XL; 09-26-2011 at 11:45 PM..
This User Gave Thanks to Chubler_XL For This Post:
pdathu
 

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LEARN ABOUT MOJAVE

cpanplus::shell

CPANPLUS::Shell(3pm)					 Perl Programmers Reference Guide				      CPANPLUS::Shell(3pm)

NAME

       CPANPLUS::Shell - base class for CPANPLUS shells

SYNOPSIS

	   use CPANPLUS::Shell; 	    # load the shell indicated by your
					    # config -- defaults to
					    # CPANPLUS::Shell::Default

	   use CPANPLUS::Shell qw[Classic]  # load CPANPLUS::Shell::Classic;

	   my $ui      = CPANPLUS::Shell->new();
	   my $name    = $ui->which;	    # Find out what shell you loaded

	   $ui->shell;			    # run the ui shell

DESCRIPTION

       This module is the generic loading (and base class) for all "CPANPLUS" shells. Through this module you can load any installed "CPANPLUS"
       shell.

       Just about all the functionality is provided by the shell that you have loaded, and not by this class (which merely functions as a generic
       loading class), so please consult the documentation of your shell of choice.

BUG REPORTS

       Please report bugs or other issues to <bug-cpanplus@rt.cpan.org<gt>.

AUTHOR

       This module by Jos Boumans <kane@cpan.org>.

COPYRIGHT

       The CPAN++ interface (of which this module is a part of) is copyright (c) 2001 - 2007, Jos Boumans <kane@cpan.org>. All rights reserved.

       This library is free software; you may redistribute and/or modify it under the same terms as Perl itself.

SEE ALSO

       CPANPLUS::Shell::Default, CPANPLUS::Shell::Classic, cpanp

perl v5.18.2							    2014-01-06						      CPANPLUS::Shell(3pm)
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