zsh not re-computing my shell prompt

Question

This might be a bit fringe, but I recently moved to zsh and am having a problem customizing my shell prompt.

Part of my .zshrc looks like this:

# kee         


        

Answer 1

You are half the way to solving this problem:

PS1='$(date)'

will show you prompt $(date), but

PS1='$(date)'
setopt promptsubst

will show you prompt Thu Aug 9 21:01:53 MSK 2012 (depends on $LANG and $LC_TIME, of course).

By the way, in the newest zsh you don’t need to use %{$fg[blue]%} anymore, there is nos %F{blue} for foreground, %K{blue} for background, %f%k for resetting them and a few others, see man zshmisc, section EXPANSION OF PROMPT SEQUENCES.

Answer 2

I ran into the same problem while customizing my prompt in zsh.

I believe this happens because the shell interpolates the value into the string once, when the prompt is initialized. Subsequent reloads have the constant string in your prompt, not the subshell interpolation.

Instead, put any lines that involve subshells into a variable defined with single quotes. Then interpolate that variable instead.

autoload -U colors && colors

local parse_special='%{$fg[yellow]%}$(date)%{$reset_color%}'

PS1="%{$fg[green]%}%n@%m %{$fg[blue]%}%c ${parse_special} %# "

Update: Adding this from ZyX's answer to make a complete solution for this. You also need to add this:

setopt promptsubst

In fact, I would suggest extracting each part of your prompt into a variable like this, including a reset_color on each. Doing so lets you change the order of prompt components without changing their implementation.