'#!/usr/bin/perl -w ' tells the perl command to turn on extra warnings with the -w option.

  


#!/usr/bin/perl -w

$i = 0;
until ($i >= 10) {
   print "Iteration $i.\n";

   $i++;
}

1.	A program that uses the -0 option.
2.	A program that uses the -l option.
3.	Edit files using the -i option.
4.	The -c Switch checks the Perl syntax without actually executing the Perl commands
5.	The -e switch executes Perl statements at the command line instead of from a script.
6.	The -n Switch: print the contents of a file or search for a line that contains a particular pattern
7.	The -w option passed to the perl command generates a warning about the code itself.
8.	Using -e option to execute the perl statement
9.	Using /e modifier to evaluate
10.	Using the -n option.
11.	Using two statements with -e option
12.	Using variable with -e option
13.	An example of the -a option.
14.	Perl can take its input from a file and send its output to a file using standard I/O redirection.
15.	Executing the Script

'#!/usr/bin/perl -w ' tells the perl command to turn on extra warnings with the -w option. : Perl Command « Language Basics « Perl