Check your type of shell first. Enter something stupit and see the rror message:

$ blabla
-bash: blabla: command not found

Bash shell:#

docu

$ PS1="\u@\h \w> "     
root@hostname /etc> 

Store permanently in /etc/profile, /etc/bashrc, ~/.bash_profile, and ~/.bashrc
means home folder.

Korn shell#

PS1="`uname -n` \$PWD> "; export PS1

Store permanently under ~/.profile