Bash has built-in support for extensive PS1 prompt customization using parameterless macros. As a result many people customize their shell prompts. There is no equivalent built-in support for PS1 customization in ksh93 but such support can easily be added using a discipline function. This post provides an example of such a PS1 discipline function.
Add the following discipline function to your ~/.kshrc and ensure that ~/.kshrc is included in your ~/.profile shell startup script which, by the way, only gets executed at login if ksh93 is your default shell.
function PS1.set
{
typeset prefix remaining=${.sh.value} var= n= k=
set -A .sh.lversion ${.sh.version}
while [[ $remaining ]]
do
prefix=${remaining%%'\'*}
remaining=${remaining#$prefix}
var+="$prefix"
case ${remaining:1:1} in
A) var+="\$(printf '%(%R)T')";;
@) var+="\$(printf '%(%H:%M %p)T')";;
d) var+="\$(printf '%(%a %b:%d)T')";;
e) var+="\$'\e'";;
h) var+=$(hostname -s);;
H) var+=$(hostname);;
j) var+="\$(jobs | wc -l)";;
l) var+="\$(basename \"\$(tty)\")";;
n) var+=$'\n';;
r) var+=$'\r';;
s) var+="\$(basename \"\$0\")";;
t) var+="\$(printf '%(%H:%M:%S)T')";;
T) var+="\$(printf '%(%I:%M:%S)T')";;
u) var+=$USER;;
v) var+="\${.sh.lversion[2]}";;
V) var+="\${.sh.lversion[2]} (\${.sh.lversion[1]})";;
w) var+="\$(pwd)";;
W) var+="\$(basename \"\$(pwd)\")";;
'#') var+=!;;
!) var+=!;;
'$') if (( $(id -u) == 0 ))
then
var+='#'
else
var+='$'
fi;;
'\') var+='\\';;
'['|']') ;;
[0-7]) case ${remaining:1:3} in
[0-7][0-7][0-7]) k=4;;
[0-7][0-7]) k=3;;
*) k=2;;
esac
eval n="\$'"${remaining:0:k}"'"
var+=$n
remaining=${remaining:k}
continue ;;
"") ;;
*) var+='\'${remaining:0:2};;
esac
remaining=${remaining:2}
done
.sh.value=$var
}
Dave Korn originally published the guts of this discipline function some 11 years ago. I have merely extended the code to include all the Bash PS1 prompt parameterless macros that I am aware of.
Here is a list of the currently supported parameterless macros:
\d : the date in "Weekday Month Date" format (e.g., "Tue May 26") \e : an ASCII escape character (033) \h : the hostname up to the first '.' \H : the hostname \j : the number of jobs currently managed by the shell \l : the basename of the shell’s terminal device name \n : a newline \r : a carriage return \s : the name of the shell (basename of $0) \t : the current time in 24-hour HH:MM:SS format \T : the current time in 12-hour HH:MM:SS format \@ : the current time in 12-hour am/pm format \A : the current time in 24-hour HH:MM format \u : the username of the current user \v : the version of ksh93 \V : the version of ksh93 and supported options \w : the current working directory, with $HOME abbreviated with a tilde \W : the basename of the current working directory, with $HOME abbreviated with a tilde \! : the history number of this command \# : the command number of this command \$ : if the effective UID is 0, #, otherwise $ \nnn : the character corresponding to the octal number nnn \\ : a backslash \[ : begin a sequence of non-printing characters \] : end a sequence of non-printing characters
Here is a screenshot showing some examples of how to customize the ksh93 PS1 prompt using the above PS1 discipline function:
Note that discipline functions are a feature of later versions of ksh93 and are NOT supported in the original Korn Shell (ksh88) or clones of the Korn Shell such as pdksh.
Enjoy!
