Getopt::Std模块简单实例

 #!/usr/bin/perl -w

use strict; # always use strict, it's a good habit
use Getopt::Std; # see "perldoc Getopt::Std"

my %options;
getopts('f:hl', /%options); # read the options with getopts

# uncomment the following two lines to see what the options hash contains
#use Data::Dumper;
#print Dumper /%options;

$options{h} && usage(1); # the -h switch, with exit option

# use the -f switch, if it's given, or use a default configuration filename
my $config_file = $options{f} || 'first.conf';

print "Configuration file is $config_file/n";

# check for the -l switch
if ($options{l})
{
 system('/bin/ls -l');
}
else
{
 my $input; # a variable to hold user input
 do  {
  print "Type 'help' for help, or 'quit' to quit/n-> ";
  $input = <>;
  print "You entered $input/n"; # let the user know what we got

  # note that 'listlong' matches /list/, so listlong has to come first
  # also, the i switch is used so upper/lower case makes no difference
  if ($input =~ /listlong/i)
  {
   system('/bin/ls -l');
  }
  elsif ($input =~ /list/i)
  {
   system('/bin/ls');
  }
  elsif ($input =~ /help/i)
  {
   usage();
  }
  elsif ($input =~ /quit/i)
  {
   exit;
  }
 }
 while (1); # only 'quit' or ^C can exit the loop
}

exit; # implicit exit here anyway

# print out the help and exit
sub usage
{
 my $exit = shift @_ || 0; # don't exit unless explicitly told so
 print <<EOHIPPUS;
first.pl [-l] [-h] [-f FILENAME]

The -l switch lists the files in the current directory, using /bin/ls -l.
The -f switch selects a different configuration file.  The -h
switch prints this help.  Without the -l or -h arguments, will show
a command prompt.

Commands you can use at the prompt:

 list:                   list the files in the current directory
 listlong:               list the files in the current directory in long format
 help:                   print out this help
 quit:                   quit the program

EOHIPPUS
 exit if $exit;
}