#!/usr/bin/perl -w
use strict;
use Fcntl ':flock';

my $dir_path  = '/home/snam/subdir';
my $lock_file = $dir_path . '/lock.lck';

# Get a 'directory lock' (note the quotes again) :)
open LOCK, '>', $lock_file
  or die "Could not lock directory '$dir_path': $!";
flock LOCK, LOCK_EX;

# Now do whatever you want with this directory.
# If all programs use the locking mechanism, they
# won't have access to this directory until you execute
# a line that says "close LOCK;" (or when the script exits)

opendir DIR, $dir_path
  or die "Could not open directory '$dir_path': $!";
my @files = readdir DIR;
closedir DIR;

for my $d (@files) {
  next if $d !~ /^[0-9]+$/;

  my $procdir = "/proc/$d";
  open IN, '<', $procdir . '/status'
    or die "Can't open status with $procdir: $!";
  while (<IN>) {
    # Fill this in yourself...
  }
}

# We're done with the directory! Let someone else access it
close LOCK;