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I have something like this in my login script that keeps $foo in the top right of my terminal. It works, but with a caveat. If I type a really long command it doesn't wrap. (Well, it'll wrap if it's more than two lines long, but the 2nd line overwrites the 1st line, if that makes sense.)

Anyone know how I can make bash wrap (i.e. insert newline) at $POS? Or even at $COLUMNS?

trunc_pwd () { # See http://www.tldp.org/HOWTO/Bash-Prompt-HOWTO/x783.html
   local pwdmaxlen=50 # Number of $PWD chars to keep
   local trunc_symbol="<" # Prepend to truncated $PWD
   if (( ${#PWD} > $pwdmaxlen )); then
      local pwdoffset=$(( ${#PWD} - $pwdmaxlen ))
      echo "${trunc_symbol}${PWD:$pwdoffset:$pwdmaxlen}"
   else
      echo ${PWD} | sed "s%^${HOME}%~%g"
   fi
}

foo="xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"

get_pos ()
{
   POS=$((COLUMNS-(${#foo}+4)))
}

if [[ ${PS1} ]]; then
   PROMPT_COMMAND='get_pos ; echo -ne "\033]0;${USER}@${HOSTNAME%%.*}:$(trunc_pwd)"; echo -ne "\007"'
   export PS1="\u@\h \W \$ \[\e[s\]\[\e[1;\$(echo -n \${POS})H\]$foo\[\e[u\]"
fi
Norma Stitz
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  • 10

1 Answers1

3

Bash uses the \[ and \] escapes in the prompt to determine the line length and where to wrap. If you enclose anything that shouldn't affect the line length (the escape sequences, the $foo, etc) with those you should be ok.

I'm not sure why your prompt isn't working (and I don't recognize some of the escape sequences like \e[s, could be you're on something other than a vt100), my attempt works just fine:

PS1='\[\e7\e[0;$((COLUMNS-(${#foo})))H$foo\e8\][\u@\h \W]\$ '

actually re-looking at yours, it might work if you change your PS1 to

PS1="\u@\h \W \$ \[\e[s\e[1;\$(echo -n \${POS})H$foo\e[u\]"

i.e., wrapping \[ ... \] around all the out-of-line stuff.

evil otto
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  • Yes, +1. (`ESC [ s` is "save cursor position", `ESC [ ; H` is "set cursor position", and `ESC [ u` is "restore cursor position".) It's attempting to print `$foo` elsewhere in the window, so the length of `$foo` should be ignored for the purposes of tracking how long the prompt on the input line is - which means that `$foo` should be inside the `\[`...`\]` as you suggest, rather than outside as in the original. – Matthew Slattery Sep 30 '11 at 23:10
  • You guys rock. `\[ ... \]` was my problem. Now with that out of the way, I love the more elegant solution of `$((COLUMNS-(${#foo})))` instead of calling a function in PROMPT_COMMAND. I'm happy and humbled. Thanks! – Norma Stitz Oct 05 '11 at 15:20
  • @evil-otto - Using your solution, how would I add color? When I try it messes up wrapping and command editing. I'm in escape sequence hell! – Norma Stitz Oct 05 '11 at 16:11
  • nm, got it. Of course in 6 months I'll never decipher this :-) `PS1="\[\e[1;32m\]\u@\h \[\e[1;34m\]\W \$ \[\e[1;31m\]\[\e[s\e[1;$((COLUMNS-(${#foo})))H$foo\e[u\]\[\e[0m\]"` – Norma Stitz Oct 05 '11 at 16:37
  • @Norma Stitz - you could always make it more readable by setting variables like `RED='\e[1;31m'; NORMAL='\e[0m';` etc, and make your prompt `PS1="${RED}\u@\h${NORMAL} ..."` or whatever you need – evil otto Oct 05 '11 at 20:01