How to Enable Open Directory Debugging

By default the MacOS X Open Directory debugging log file is disabled. You can temporarily reenable it by running the following command in the Terminal app:

sudo killall -USR1 DirectoryService

After you reboot, debugging will be disabled again. If you want to enable Open Directory debugging so that it stays enabled across reboots, run the following command in the Terminal app:

touch /Library/Preferences/DirectoryService/.DSLogAtStart

To disable debugging again just delete that file:

sudo rm /Library/Preferences/DirectoryService/.DSLogAtStart

The debugging log file is located at:


Leopard ByHost Plist Preference File Naming Convention Change

In Mac OS X 10.4 Tiger some system preferences were unique to a particular computer and so were named using a naming convention that included the MAC address of the first network device in the computer (en0). In Mac OS X 10.5 Leopard this naming convention was changed to use a different unique identifier other than the first network adapter’s MAC address. Leopard now uses something called the UUID for this unique identifier. You can determine a UUID of a Leopard computer by running the terminal command:

ioreg -rd1 -c IOPlatformExpertDevice | grep -E '(UUID)'


How To Determine Dynamic Library Dependencies For An Executable or Library File in OS X

This script uses otool -L to determine and print all dynamic library dependencies of a given executable or library file recursively and you use it like this:

$ /bin/ls

Here’s the script which was written by Marc Liyanage:

# Written by Marc Liyanage <>
# use strict;
use warnings; 

my ($file) = @ARGV;
die $! unless (-f $file); 

my $libs = {};
check_libs(file => $file, libs => $libs); 

	map {("\n$_:\n", map {"\t$_\n"} sort {lc($a) cmp lc($b)} @{$libs->{$_}})}
	sort {lc($a) cmp lc($b)}
	grep {@{$libs->{$_}}}
sub check_libs {
	my (%args) = @_;
	my $libs = $args{libs};
	my @file_libs = grep {$_ ne $args{file}} grep {$_} map {/^\s+(\S+)/} qx(otool -L $args{file});
	$libs->{$args{file}} = \@file_libs;
	foreach my $lib (grep {!$libs->{$_}} @file_libs) {
		unless (-f $lib) {
			$libs->{$lib} = ['(missing)'];
		check_libs(%args, file => $lib);

In case my blog software mangles the code above, you can download the script in a plain text file by clicking here: