Reasonable PS1 with system ksh

netbsdnoob

Hello everyone i am using the system provided ksh /bin/ksh and I was wondering if there was a nice PS1 prompt I could use similar to what I used to use in bash, i.e.:

Symbol $ or # depending if the user is root
Show ~ if I am in the home directory
Some colors (you can show me with random colors, i will set them accordingly)

Can anybody help me?

rvp

netbsdnoob Here.

nettester

I use this (with mksh but i guess it'll work with NetBSD ksh too):

HOSTNAME="$( hostname )"
EUSER="$( id -un )"
if [ "$EUSER" = root ]; then
	PS1=$'[\e[37;1m$EUSER@$HOSTNAME:${PWD/#$HOME/\\~}\e[0m]# '
else
	PS1=$'[\e[37;1m$EUSER@$HOSTNAME:${PWD/#$HOME/\\~}\e[0m]$ '
fi

Probably not exactly elegant (and i guess you can get away with just using $USER instead of defining and using $EUSER on a system that's a little more sane than Linux) but it does the job. There's also colors (those \e[... codes) in it even if color just means bright white. You can put pretty much any ansi escape sequence in your shell prompt even if a lot of them don't make to much sense there. Wikipedia has a pretty extensive list: https://en.wikipedia.org/wiki/ANSI_escape_code

netbsdnoob

nettester unfortunately it does not work,
I get: ksh: : bad substitution

can it be that you are using something specific to your mksh?

netbsdnoob unfortunately it does not work,

ksh does not support the same prompt syntax as bash. Google it/Duck duck go it, whatever you fancy ... but, do some reading.

It's possible to do it but, it has been a long time since I've used ksh and those dotfiles are long gone. So, ... go figure.

nettester

netbsdnoob My bad. @pin is right. I just tried and the configuration i use doesn't even remotely work with NetBSD's ksh. I didn't think mksh would differ that much. Sorry.

PS1="$( printf '[\e[37;1m$USER@$HOST:foo\e[0m]# ' )"

This at least correctly includes the ansi escapes but i don't know how to fix the substitution (or how to make it evaluate the prompt at display time which is needed to get the current value for $PWD and not just whatever value it had when $PS1 was defined) for $HOME.

By the way: I noticed the hostname is already available as $HOST and NetBSD probably isn't doing any funky things to $USER in relation to su so setting up $EUSER and $HOSTNAME like in my earlier code is generally superfluous.

Overlord1310

netbsdnoob

Greetings. Currently, I'm using a GNU/Linux distribution and I'm planning to switch to NetBSD on a computer that I'll receive in a couple of days. In my current distribution, I also use the Korn shell and have configured my prompt in the following manner:

My prompt consists primarily of parameter substitutions and a function to determine the Git branches I have (this is visible when necessary).
I've assigned colors to make it visually appealing.
My prompt is invoked through a function from my interactive shell file.

The main function calling my prompt is composed as follows:

function prompt {
    print "${GREEN}${PWD/$HOME/\~} ${CYAN}$(get_branch)"
    print "${RED}-> ${YELLOW}$ ${NORM}"
}

PS1="\$(prompt)"

The function determining the current branch in Git repositories is set up as follows:

function get_branch {
    BRANCH=$(git rev-parse --abbrev-ref HEAD 2> /dev/null)
    if [[ ! -z ${BRANCH} ]]; then
        print "${BRANCH}"
    fi

    unset BRANCH
}

The colors are defined as follows:

GREEN=$(printf '%b' "\033[1;32m")
CYAN=$(printf '%b' "\033[1;36m")
RED=$(printf '%b' "\033[1;31m")
YELLOW=$(printf '%b' "\033[1;33m")
NORM=$(printf '%b' "\033[0m")

In my interactive shell configuration ($HOME/.kshrc), I load my prompt as follows:

. $HOME/.local/funcs/prompt

Lastly, here's a sample of how my prompt looks

As you can see, the configuration of my prompt isn't too complicated, so I don't believe it would be too difficult for you to modify it to suit your needs.

Regarding the prompt I use for the root account, I also have it customized through a function. The content of the function is as follows:

function admin_prompt {
    [[ $PWD == $HOME ]] && dir="~" || dir="${PWD#*/}"
    print "${YELLOW}[$dir] ${GREEN}#${RED} "
}

PS1="\$(admin_prompt) "

Similar to my personal prompt, the root account's prompt is loaded through its own interactive shell configuration (root home: .shrc).

. $HOME/.local/funcs/admin_prompt

This is how the prompt looks when I switch to the root account.

kc9udx

man is user's best friend. (At least with NetBSD)

netbsdnoob

nettester Thanks for the attempt, I will try to read more and solve the riddle, or wait for somebody else to help.

nettester

netbsdnoob Any time. By the way: It seems @rvp already gave you some working code. It's kinda tricky but i guess ksh simply doesn't have a feature to evaluate variables at display time so overloading cd is probably the way to go if you want to display the current directory in your prompt.

rvp

netbsdnoob This works with NetBSD's ksh, ksh93, dash and bash:

PS1='$( printf "\\033[1;37m" )'\
'$( id -un )@$( expr $(hostname) : "\([^.]*\)" ) '\
'$( X="$PWD/"; Y="$HOME/"; '\
'   [ "${X#$Y}" = "$PWD/" ] && echo "$PWD" || echo "~${PWD#$HOME}" ) '\
'$( printf "\\033[0m" )'\
'$( [ $(id -u) -eq 0 ] && echo "#" || echo "$" ) '

Be careful copy exactly as shown, and not leave any trailing blanks. NetBSD's /bin/sh will need a set -o promptcmds (if that option exists in the shell).

EDIT: Use a different method instead of expr as the RHS string (ie. the path) may have blanks or regex meta-chars which will need to be quoted.

netbsdnoob

rvp
Woow pretty cool, almost perfect, still one issue.

If i am in $HOME this prints ~ correctly as it should
But now if i am in $HOME/.config/myconfig/whatever I have in my prompt:

/home/username/.config/myconfig/whatever

So is there any way to fix this too?

rvp

netbsdnoob My bad. Fixed.

netbsdnoob

rvp great! Loved it!

Do you know by any chance how can i bind Ctrl+L to clear and Alt+. to loop over the list of previous arguments as it happens in bash?

Oh also ctrl+arrow keys would be cool to have

rvp

netbsdnoob ksh(1) should tell you create macros for the last 2 functions you want. For Ctrl-L, it doesn't look like there's any editing command to clear the screen. You'll probably have to hack the source to add such a feature.

yeti

I like it boring:

(yeti@tilde.institute:p3)~/opt/tcc/src/tinycc$ git -P branch 
* mob
(yeti@tilde.institute:p3)~/opt/tcc/src/tinycc$ du -sh .
10.2M   .

Where I am (user, host, pwd and a kind of pty number) helps navigating and the only luxury I add is ...

 Num Name                                                                  Flags

   0 (yeti@tilde.institute:p0)~$ _                                              
   1 (yeti@tilde.institute:p1)~/public_gemini$ _                                
   2 (yeti@tilde.institute:p2)~/public_html$ _                                  
   3 (yeti@tilde.institute:p3)~/opt/tcc/src/tinycc$ _

... that my PS1 tells screen to to rename the window to look like the current prompt and that even works fine over ssh too:

 Num Name                                                                  Flags

   0 (yeti@kumari:1)~$ _                                                       $
   1 (yeti@kumari:2)/tmp/mc-yeti$ _                                            $
   2 (yeti@pi1-b:5)/etc/tor$ _                                                 $
   3 (yeti@tilde.institute:ql)~/opt/a-fake-bonsai$ _                           $
   4 (yeti@kumari:5)~$ _                                                       $

That's too silly?

I think these ™should be™ the relevant parts of my .kshrc:

##
## build a PS1
##
HOST=$(hostname)
TTY=$(tty)
LYN=${TTY#/dev/tty}
case ${TERM:-dumb} in
screen*)
        PS1='\[\ek(\u@$HOST:$LYN)\w\$ _\e\134\](\u@$HOST:$LYN)\w\$ '
        ;;
xterm*)
        PS1='(\u@$HOST:$LYN)\w\$ '
        ;;
esac

rvp

yeti

PS1='\[\ek(\u@$HOST:$LYN)\w\$ _\e\134\](\u@$HOST:$LYN)\w\$ '

Does that \[...\] demarcation work in ksh now? I thought that was bash-only.

yeti

rvp OpenBSD's KSH understands the BASHy way of doing this (and the lines above were from OpenBSD) and NetBSD's needs to get this told in a different way and I only assumed its KSH would accept that in the same way as on OpenBSD-KSH and in BASH and in YASH ... sigh.

man 1 ksh on NetBSD:

       PS1    PS1 is the primary prompt for  interactive  shells.   Parameter,
              command and arithmetic substitutions are performed, and ! is re‐
              placed with the current command number (see fc  command  below).
              A literal ! can be put in the prompt by placing !! in PS1.  Note
              that since the command line editors try to figure out  how  long
              the  prompt  is  (so  they  know  how  far  it is to edge of the
              screen), escape codes in the prompt tend to mess things up.  You
              can  tell  the shell not to count certain sequences (such as es‐
              cape codes) by prefixing your prompt with a non-printing charac‐
              ter  (such  as control-A) followed by a carriage return and then
              delimiting the escape codes with  this  non-printing  character.
              If  you  don't  have  any non-printing characters, you're out of
              luck...  BTW, don't blame me for this hack; it's in the original
              ksh.  Default is `$ ' for non-root users, `# ' for root.

rvp

yeti I only assumed its KSH would accept that in the same way as on OpenBSD-KSH and in BASH and in YASH ... sigh

So, there is a common method which works on all KornShells to mark non-countable chars. in PS1.