Set prompt to fqdn - domain.toplevel

gistfile1.sh

# This will change your prompt and screen/tmux tab title based on how many
# fields there are in the FQDN.  For a normal 3 field FQDN, it will use $HOSTNAME
# like normal.  For 4+ fields it will set it to field1.field2. 

# Rename screen window
function rename_screen_tab () { echo -ne "\x1bk$@\x1b\\"; return 0; }

MYHOST=`echo $HOSTNAME | sed 's/[.][^.]*[.][^.]*$//'`
[[ $TERM == "screen" ]] && PROMPT_COMMAND='rename_screen_tab ${MYHOST}'
PS1="\d \A \w\n\u@$MYHOST > "