OS X PERMANENT STATIC ROUTE

cd /Library/StartupItems

sudo mkdir StaticRoutes
cd StaticRoutes

Create file StaticRoutes
sudo nano StaticRoutes

#!/bin/sh
# Set up static routing tables
# Roark Holz, Thursday, April 6, 2006

. /etc/rc.common
StartService ()
{
ConsoleMessage "Adding Static Routing Tables"
route add -net 192.168.20.0/24 192.168.0.2
}

StopService ()
{
return 0
}

RestartService ()
{
return 0
}

RunService "$1"

Create file StartupParameters.plist
sudo nano StartupParameters.plist

{
Description = "Add static routing tables";
Provides = ("StaticRoutes");
Requires = ("Network");
OrderPreference = "None";
}

Set as an executable file:
sudo chmod 755 StaticRoutes StartupParameters.plist

To view routes:
netstat -r

USERS AND GROUPS IN LINUX

Display users details: sudo id <user>

Add group: sudo groupadd <group>

Create user and add to group: sudo useradd -g <group> <user>

Add user to a group: sudo usermod -a -G <group> <user>

Change a users primary group: sudo usermod -g <group> <user>

CHANGE LEOPARD LOGIN WALLPAPER

sudo cp /<path-to-image-file>/<image-file.jpg> /System/Library/CoreServices/DefaultDesktop.jpg