rbenv version display in zsh right-prompt not refreshing

Question

I have the following code in my .zshrc:

local ruby_version=''
if which rvm-prompt &> /dev/null; then
  ruby_version="$(rvm-prompt i v g)"
else
  if which rbenv &> /dev/null; then
    ruby_version="$(rbenv version | sed -e "s/ (set.*$//")"
  fi
fi

And I have this code in my RPS1 prompt:

RPS1='${PR_GREEN}$(virtualenv_info)%{$reset_color%} ${PR_RED}${ruby_version}%{$reset_color%}'

(For brevity sake I have not shown the code that sets the PR_ colors or determines the virtual environment - both of those work.)

When a new shell is created (new window or new tab in iTerm2) the Ruby information is correct. However if I switch to a project that uses a different Ruby, as determined by the .ruby-version file, the Ruby information displayed in the right prompt does not refresh. If I re-source my .zshrc file the right-prompt does refresh.

Do I need to encase the code that determines the Ruby version in a function? By the way, I do have setopt promptsubst in my .zshrc as well.

What am I missing that is preventing the right-prompt from refreshing when I change directories?

If I surround the `$(rbenv version | see -e "s/ (set.$//")` line with single quotes, then I see that string in my right-prompt. When that line is surrounded with double-quotes as shown in the original question, then I see the current Ruby only after sourcing `~/.zshrc`. — Mark Nichols, Jan 31 '13 at 23:57

score 5 · Accepted Answer · answered Feb 01 '13 at 03:28

You should not be using this code

local ruby_version=''
if which rvm-prompt &> /dev/null; then
  ruby_version="$(rvm-prompt i v g)"
else
  if which rbenv &> /dev/null; then
    ruby_version="$(rbenv version | sed -e "s/ (set.*$//")"
  fi
fi

directly in zshrc: it won’t update ruby_version variable when switching to another project. You can change it to

function ruby_version()
{
    if which rvm-prompt &> /dev/null; then
      rvm-prompt i v g
    else
      if which rbenv &> /dev/null; then
        rbenv version | sed -e "s/ (set.*$//"
      fi
    fi
}

and change ${ruby_version} in your prompt to $(ruby_version). Or, if you are sure you don’t need checking this on each prompt (it will slow things down) you can use

function _update_ruby_version()
{
    typeset -g ruby_version=''
    if which rvm-prompt &> /dev/null; then
      ruby_version="$(rvm-prompt i v g)"
      rvm-prompt i v g
    else
      if which rbenv &> /dev/null; then
        ruby_version="$(rbenv version | sed -e "s/ (set.*$//")"
      fi
    fi
}
chpwd_functions+=(_update_ruby_version)

, it will update ruby_version only when you change current directory. Also note that your code is misleading: local ruby_version='' that is put directly into zshrc is equivalent to typeset -g ruby_version='' or just plain ruby_version='' which defines global, but not exported variable. There are no file-local variables in zsh (except for autoload files that actually represent functions).

Both of these variations worked perfectly. Thank you. I've implemented the second of the two, using the `chpwd_functions` line to only test the Ruby version when a directory changes. The only time this may be an issue is setting up a new project that has a local Ruby. After issuing the `rbenv local` command to define that Ruby, I'll have to leave the pwd and return to reset the prompt - a minor detail. Thanks again. — Mark Nichols, Feb 01 '13 at 04:08
@MarkNichols You don’t need to change directory two times. Just use `cd .`: it triggers `chpwd` hook, but does not actually change directory. — ZyX, Feb 01 '13 at 13:51
You don't need to run sed. rbenv has a command for version only. Just you rbenv version-name and you will get only the version you are looking for. — Fa11enAngel, Jul 14 '13 at 11:54
@Fa11enAngel I have no rbenv on my system and I know almost nothing about ruby development, just copied code from the question. Will not edit the post as OP may have had a reason for using `sed`: i.e. old versions of `rbenv` do not support `version-name`. — ZyX, Jul 14 '13 at 11:59

mpapis · Answer 2 · 2013-02-01T08:21:30.593

1

use this one:

export ruby_version
if
  which rvm-prompt &> /dev/null
then
  ruby_version='$(rvm-prompt i v g)'
elif
  which rbenv &> /dev/null
then
  ruby_version='$(rbenv version | sed -e "s/ (set.*$//")'
else
  ruby_version=''
fi

RPS1='${PR_GREEN}$(virtualenv_info)%{$reset_color%} ${PR_RED}'"${ruby_version}"'%{$reset_color%}'

this will inject the ruby_version variable code into the RPS1

edited Feb 01 '13 at 08:21

answered Jan 31 '13 at 23:59

mpapis

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Using the above code my RPROMPT displays the text inside the single-quotes. Like so, `$(rbenv version | sed -e "s/ (set.*$//")`. Changing the single-quotes to double-quotes returns me to the original, incorrect, behavior. – Mark Nichols Feb 01 '13 at 03:31

lmcanavals · Answer 3 · 2013-02-01T03:50:35.943

Looks like you need to use the precmd hook which is executed every time you execute commands, like switching folders. Unlike the way you did it, that is only executed once when you start a new instance.

precmd () {

  local ruby_version=''
  if which rvm-prompt &> /dev/null; then
    ruby_version="$(rvm-prompt i v g)"
  else
    if which rbenv &> /dev/null; then
      ruby_version="$(rbenv version | sed -e "s/ (set.*$//")"
    fi
  fi

  #you can use RPROMPT
  RPS1='${PR_GREEN}$(virtualenv_info)%{$reset_color%} ${PR_RED}${ruby_version}%{$reset_color%}'
}

Make sure to not override this function, create it only if it wasn't created somewhere else. B Because it's very likely that it is already defined somewhere in your .zshrc or other zsh related files, especially if you are using something like oh-my-zsh or something else that shows git (or some other version control) information on the prompt or things like that.

Some more light on the matter.

I wrapped the RPROMPT with precmd after verifying that non of my zsh configuration has a precmd elsewhere. I was using on-my-zsh, but found it slow and therefore I'm rolling my own configuration now. There was no change in the behavior of the RPROMPT. I'll have to continue reading the zsh manual. — Mark Nichols, Feb 01 '13 at 03:34

rbenv version display in zsh right-prompt not refreshing

3 Answers3