## PERL SCRIPT ##

#!/usr/bin/perl;
use strict;

my $g_commonMount = "/common_mount";
my $g_moduleDir = "$g_commonMount/include";

sub fileWatcher
{
   while(1)
   {
      if ( -d $g_moduleDir )
      {
         use autouse 'foo' => qw/foo/;  #using your example
         unshift @INC, '$g_moduleDir';  #foo.pm is under $g_moduleDir
         foo;
      }

      sleep (10);

   }
}

#### MAIN ###
&fileWatcher;

__END__