...
     prompt  The string which is printed before reading each com-
             mand  from  the terminal.  prompt may include any of
             the following formatting sequences  (+),  which  are
             replaced by the given information:

             %/  The current working directory.
             %~  The current working directory,  but  with  one's
                 home  directory  represented  by  `~'  and other
                 users' home directories represented  by  `~user'
                 as    per    Filename    substitution.   `~user'
                 substitution  happens  only  if  the  shell  has
                 already  used  `~user'  in  a  pathname  in  the
                 current session.
             %c[[0]n], %.[[0]n]
             %c[[0]n], %.[[0]n]
                 The trailing component of  the  current  working
                 directory, or n trailing components if a digit n
                 is given.  If n begins with `0', the  number  of
                 skipped    components   precede   the   trailing
                 component(s) in the format `/<skipped>trailing'.
                 If  the  ellipsis shell variable is set, skipped
                 components are represented by an ellipsis so the
                 whole  becomes  `...trailing'.  `~' substitution
                 is done as in `%~' above, but the `~'  component
                 is ignored when counting trailing components.
             %C  Like %c, but without `~' substitution.
             %h, %!, !
                 The current history event number.
             %M  The full hostname.
             %m  The hostname up to the first `.'.
             %S (%s)
                 Start (stop) standout mode.
             %B (%b)
                 Start (stop) boldfacing mode.
             %U (%u)
                 Start (stop) underline mode.
             %t, %@
                 The time of day in 12-hour AM/PM format.
             %T  Like `%t', but in 24-hour format  (but  see  the
                 ampm shell variable).
             %p  The `precise' time of day in 12-hour AM/PM  for-
                 mat, with seconds.
             %P  Like `%p', but in 24-hour format  (but  see  the
                 ampm shell variable).
             \c  c is parsed as in bindkey.
             ^c  c is parsed as in bindkey.
             %%  A single `%'.
             %n  The user name.
             %d  The weekday in `Day' format.
             %D  The day in `dd' format.
             %w  The month in `Mon' format.
             %W  The month in `mm' format.
             %y  The year in `yy' format.
             %Y  The year in `yyyy' format.
             %l  The shell's tty.
             %L  Clears from the end of the prompt to end of  the
                 display or the end of the line.
             %#  `>' (or the first character of  the  promptchars
                 shell  variable)  for  normal users, `#' (or the
                 shell  variable)  for  normal users, `#' (or the
                 second  character  of   promptchars)   for   the
                 superuser.
             %{string%}
                 Includes string as a  literal  escape  sequence.
                 It should be used only to change terminal attri-
                 butes and should not move the  cursor  location.
                 This cannot be the last sequence in prompt.
             %?  The return code of  the  command  executed  just
                 before the prompt.
             %R  In  prompt2,  the  status  of  the  parser.   In
                 prompt3,  the corrected string.  In history, the
                 history string.

             `%B', `%S', `%U' and `%{string%}' are available only
             in  eight-bit-clean  shells;  see  the version shell
             variable.

             The bold, standout and underline sequences are often
             used to distinguish a superuser shell. For example,

                 > set prompt = "%m [%h] %B[%@]%b [%/] you  rang?
                 "
                 tut [37] [2:54pm] [/usr/accts/sys] you rang? _

             Set by default to `%# ' in interactive shells.