Conditional PS1

Question

I'm basically trying to make my PS1 look like this when in a git repo:

$ ~/Projects/Blah (master):

Or if I'm not in a Git repo, I want it to look like this:

$ ~/Projects/Blah:

This is my current PS1:

export PS1="$ \w \$(__git_ps1): "

It works for the git repo output, but the problem is that if I'm not in a git repo, the output looks like this:

$ ~/Projects/Blah :

I don't really want that space there if it isn't a git repo, is there some way I can specify this in my PS1?

Answer 1

I use a function to set my prompt dynamically. Here is my particular function, defined in my development environment initialisation script:

function prompt_cmd
{
  # Tell the terminal application (using escape sequences) what the CWD is.
  # (this comes from /etc/bashrc)
  update_term_cwd

  if [[ "$ORIG_PS1" == "" ]]; then
    export ORIG_PS1=$PS1
  fi

  if [[ "$CURRENT_PROJECT" == "" ]]; then
    export PS1=$ORIG_PS1
  else
    if [[ "$PWD" == "$DEV_HOME/projects/$CURRENT_PROJECT"* ]]; then
       PWD_COLOR=''
    else
       PWD_COLOR='\[\e[0;31m\]'
    fi
    export PS1="\[\e[0;32m\]$CURRENT_PROJECT\[\e[m\]:$PWD_COLOR\W\[\e[m\]$ "
  fi
}

(it sets the path part of the prompt to red if I happen to drift out of the project I think I'm in!)

...then tell bash to use the function:

export PROMPT_COMMAND=prompt_cmd

Answer 2

What I do for this kind of thing is to change the value of PS1 when I change directories. This is trivial in zsh which executes the chpwd command; it can be done in bash by defining wrappers around cd and friends.

cd () { builtin cd "$@" && chpwd; }
pushd () { builtin pushd "$@" && chpwd; }
popd () { builtin popd "$@" && chpwd; }
chpwd () {
  if git rev-parse --show-toplevel 2>/dev/null >/dev/null; then
    PS1='$ \w $(__git_ps1): '
  else
    PS1='$ \w: '
  fi
}

Answer 3

I ended up using this .git-prompt.sh file. Steps to get this to work:

1. Create a file called .git-prompt.sh in your home directory (~/.git-prompt.sh) and copy the code from the link above into it.
2. In your .bash_profile or .bashrc file, add this line: source ~/.git-prompt.sh
3. Change your PS1 to this: PS1='\n$ \w$(__git_ps1 " (%s)"): '

Answer 4

A one-liner:

PS1='\[\e]0;$( [ "$PS1TITLE" == "" ] || echo -n "$PS1TITLE  :  ")${debian_chroot:+($debian_chroot)}\u@\h: \w\a\]${debian_chroot:+($debian_chroot)}\[\033[01;31m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\w\[\033[00m\]\$ '

When the variable PS1TITLE is set, its contents shows up in the window's titlebar.

Explanation:

PS1='...'

Make no variable expansion.

PS1='...$( [ "$PS1TITLE" == "" ] || echo -n "$PS1TITLE  :  ")...'

Execute a test: if variable "PS1TITLE" is empty, do not display it. If the string exists and is non-empty, it is displayed with a colon.

The rest of the PS1 string is taken from a Debian system's .bashrc.

Bash executes PS1 every time prompt is displayed and updates everything accordingly.

Answer 5

# .bashrc example edits to PS1 for git

With Abbreviated Paths:

    # -- With color:
    PS1='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\W\[\033[01;33m\]$([[ "$(git branch --show-current 2>/dev/null)" == "" ]] || echo " ("$(git branch --show-current 2>/dev/null)")")\[\033[00m\]\$ '

    # -- Without color:
    PS1='${debian_chroot:+($debian_chroot)}\u@\h:\W$([[ "$(git branch --show-current 2>/dev/null)" == "" ]] || echo " ("$(git branch --show-current 2>/dev/null)")")\$ '

As Requested:

    # -- With color:
    PS1='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\w\[\033[01;33m\]$([[ "$(git branch --show-current 2>/dev/null)" == "" ]] || echo " ("$(git branch --show-current 2>/dev/null)")")\[\033[00m\]: '

    # -- Without color:
    PS1='${debian_chroot:+($debian_chroot)}\u@\h:\w$([[ "$(git branch --show-current 2>/dev/null)" == "" ]] || echo " ("$(git branch --show-current 2>/dev/null)")"): '