Put this in your
$PROMPT will undergo parameter expansion (as well as its siblings command substitution and arithmetic expansion) each time it's displayed. Take care to quote anything that gets included from an outside source properly. Also note that the result of the
$ expansion will undergo
% expansion (i.e. prompt escape sequences can appear in
An alternate approach is to reset the
PROMPT variable itself in
precmd, but this makes it harder to customize the prompt in a specific shell instance.