How do we use perl to list out all the files in a directory and subdirectories?

Answer:

Here is a routine that'll recurse a given directory (perl script.pl /path/to/search/).

Code:

#!/usr/bin/perl -w

use strict;

sub recurse($) {
  my($path) = @_;

  ## append a trailing / if it's not there
  $path .= '/' if($path !~ /\/$/);

  ## print the directory being searched
  print $path,"\n";

  ## loop through the files contained in the directory
  for my $eachFile (glob($path.'*')) {

    ## if the file is a directory
    if( -d $eachFile) {
      ## pass the directory to the routine ( recursion )
      recurse($eachFile);
    } else {

      ## print the file ... tabbed for readability
      print "\t",$eachFile,"\n";
    }
  }
}

## initial call ... $ARGV[0] is the first command line argument
recurse($ARGV[0]);
 

Note:

What does my($path) = @_; do?

@_ is a special variable that holds the arguments of a subroutine. 

This is why you don't see this in perl: sub newSubroutine($arg1,$arg2);

Instead you can do the following:

Code:

#!/usr/bin/perl -w

use strict;

sub newSubroutine {
  for my $eachArg (@_) {
    print $eachArg,"\n";
  }
}

newSubroutine('some','random','number','of','arguments');

So it's very similar to $_ only it's used with lists.

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