使用 Getopt::Std 的命令行开关

Unix 用户非常熟悉基于文本的 UI 模型。设想有一个 Perl 程序，让我们先看一下这个模型用于该程序的简单实现。标准的 Getopt::Std 模块简化了命令行参数的解析。这个程序仅仅为了说明 Getopt::Std 模块（没有实际用途）。 请参阅本文后面的参考资料。

				
						
#!/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();			# the -h switch

# 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
{
 system('/bin/ls');
}

# print out the help and exit
sub usage
{
 print <first.pl [-l] [-h] [-f FILENAME]

Lists the files in the current directory, using either /bin/ls or
/bin/ls -l.  The -f switch selects a different configuration file.
The -h switch prints this help.
EOHIPPUS
exit;
}