sudo pmset -a sleep 0; sudo pmset -a disablesleep 1
sudo pmset -b sleep 5; sudo pmset -b disablesleep 0
pmset sleep - system sleep timer (value in minutes, or 0 to disable)
pmset disablesleep 1 - permanently disable sleep
The -a, -b, -c, -u flags determine whether the settings apply to battery ( -b ), charger (wall power) ( -c ), UPS ( -u ) or all ( -a ).