zsh prompt wrapping to a newline after adding buildstatus

Question

I'm attempting to add my Buildkite (ci build server) project status to the zsh prompt! I've written a ruby script that pulls the status and puts it into a colon separated file in the following format:

# .buildkite_status
project1: √
project2: x

The √ and x are ansi colour coded.

And I have a prompt that works fine until I add my $ci_build variable/function to the RPROMPT!

At the moment my prompt looks like;

~/.dotfiles »                                         ± master*:3cce1cb

and after the change I want

~/.dotfiles »                                         ± master*:3cce1cb √

The problem I'm facing is the introduction of the ci_build is now wrapping my prompt. after a week of reading docs and tweaking, I'm out of suggestions. I really would love this to work, but would prefer it working correctly.

Here is an image of the problem: https://www.dropbox.com/s/ufj82ipd7bm0o30/Screenshot%202015-06-11%2016.52.11.png?dl=0

zsh.rc

build_status() {
  current_directory=$(basename $PWD)
  var=$(cat ~/.buildkite_status | grep \^$current_directory: | awk -F':' '{print $2}')
  echo -n $var | tr '\n' ' '
}

local git_formats="%{${fg_bold[yellow]}%}± %b%c%u:%.7i%{${reset_color}%}"
zstyle ':vcs_info:git*' enable git
zstyle ':vcs_info:git*' check-for-changes true
zstyle ':vcs_info:git*' get-revision true
zstyle ':vcs_info:git*' stagedstr "+"
zstyle ':vcs_info:git*' unstagedstr "*"
zstyle ':vcs_info:git*' formats "$git_formats"
zstyle ':vcs_info:git*' actionformats "%a $git_formats"

precmd() {
  vcs_info
  build_status
}

zle-keymap-select() { zle reset-prompt; }
zle -N zle-keymap-select

VI_MODE_INDICATOR="%{$fg_bold[red]%}<%{$fg[red]%}<<%{$reset_color%}"
vi_mode_prompt_info() {
  echo "${${KEYMAP/vicmd/$VI_MODE_INDICATOR}/(main|viins)/}"
}

local cwd='%{${fg_bold[green]}%}$(prompt_pwd)%{${reset_color}%}'
local usr='%{${fg[yellow]}%}$(user_hostname)%{${reset_color}%} '
local char='%(?,%F{cyan}»,%F{red}»)%f '
local git='${vcs_info_msg_0_}$(git_stash) '
local git_author='$(git author > /dev/null || echo "$(git author) ")'
local vi_mode='$(which vi_mode_prompt_info &> /dev/null && vi_mode_prompt_info) '
local bg_job='%{${fg_bold[black]}%}$(prompt_bg_job)%{${reset_color}%} '
local ci_build='%{$(build_status)%} '

PROMPT=$cwd$usr$char
RPROMPT=$vi_mode$bg_job$git_author$git$ci_build

Answer 1

The issue is caused by the way you include the output of build_status:

local ci_build='%{$(build_status)%} '

According to the zsh manual

%{...%}

Include a string as a literal escape sequence. The string within the braces should not change the cursor position

zsh assumes that $ci_build contains only escape sequences and prints out to a length of 0 characters, while it also contains the character showing the status and a space, thus being actually 2 characters longer.

As there is no actual right-alignment in the terminal zsh calculates the position of the right prompt from its perceived length. As it is 2 characters longer then calculated the right prompt wraps over the end of line, placing the cursor on the next line.

The quick fix for this problem is to use %G inside %{...%} to tell zsh that there are characters that will be output. %G stands for one character, for more characters you can either use the appropriate amount of %G or put the matching number between % and G:

local ci_build='%{$(build_status)%2G} '

---

The cleaner fix would be to keep the ANSI codes (and possibly the special characters you are using) out of the status file and just use zsh features for that.