calc_hash.perl

#!/usr/texbin/perl

use strict;
use warnings;

my $ROOT = "/Volumes/DATA/Dropbox/Research/Papers2/"; # dir holding data files
#my $ROOT = "$ENV{HOME}/Downloads/Test/SRC"; # dir holding data files
my $META = "$ENV{HOME}/Downloads/Test/DEST"; # dir holding meta files

my %FILE_TO_DATE = file_hash( $ROOT );
my %META_TO_DATE = file_hash( $META );

for my $file (sort keys %FILE_TO_DATE) {
my $fdate = $FILE_TO_DATE{$file};
my $mdate = $META_TO_DATE{$file};
defined $mdate and $mdate gt $fdate and next;
update_meta("$ROOT/$file", "$META/$file");
}

sub update_meta {
my ($file, $meta) = @_;
my $meta_dir = $meta;
$meta_dir =~ s{/[^/]+$}{};

print "Updating: $file\n";
-d $meta_dir or system("mkdir", "-p", $meta_dir);

system("touch", $meta); # YOUR UPDATE COMMAND GOES HERE
}

sub file_hash {
my $dir = shift;
# my @files = `find $dir -type f -printf '%p:%C+\n'`;
my @files = `find $dir -type f -print0 | xargs -0 stat -f '%p+\n'`;
for (@files) {
chomp;
s{^$dir/}{};
}
return map { split(/:/, $_, 2) } @files;
}