[quote] How to read Perl command-line arguments.

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How to read Perl command-line arguments


By Alvin Alexander. Last updated: Aug 11, 2013　　Perl FAQ: How do I read command-line arguments in Perl?
　　Note: If you want to handle simple Perl command line arguments, such as filenames and strings, this tutorial shows how to do that. If you want to handle command-line options (flags) in your Perl scripts (like "-h" or "--help"), this new Perl getopts command line options/flags tutorial is what you need.

Perl command line args and the @ARGV array
　　With Perl, command-line arguments are stored in a special array named @ARGV. So you just need to read from that array to access your script's command-line arguments.
　　ARGV array elements: In the ARGV array, $ARGV[0] contains the first argument, $ARGV[1] contains the second argument, etc. So if you're just looking for one command line argument you can test for $ARGV[0], and if you're looking for two you can also test for $ARGV[1], and so on.
　　ARGV array size: The variable $#ARGV is the subscript of the last element of the @ARGV array, and because the array is zero-based, the number of arguments given on the command line is $#ARGV + 1.

Example 1: A typical Perl command line args example
　　A typical Perl script that uses command-line arguments will (a) test for the number of command line arguments the user supplied and then (b) attempt to use them. Here's a simple Perl script named name.pl that expects to see two command-line arguments, a person's first name and last name, and then prints them:

#!/usr/bin/perl -w
# (1) quit unless we have the correct number of command-line args
$num_args = $#ARGV + 1;
if ($num_args != 2) {
print "\nUsage: name.pl first_name last_name\n";
exit;
}
# (2) we got two command line args, so assume they are the
# first name and last name
$first_name=$ARGV[0];
$last_name=$ARGV[1];
print "Hello, $first_name $last_name\n";

　　This is fairly straightforward, where adding 1 to $#ARGV strikes me as the only really unusual thing.
　　To test this script on a Unix/Linux system, just create a file named name.pl, then issue this command to make the script executable:

chmod +x name.pl

　　Then run the script like this:

./name.pl Alvin Alexander

　　Or, if you want to see the usage statement, run the script without any command line arguments, like this:

./name.pl