Ubuntu – Git Branch in ZSH Prompt

The man page of bash has a section PROMPTING (shouting in the original), from which I only cite the beginning:

PROMPTING When executing interactively, bash displays the primary prompt PS1 when it is ready to read a command, and the secondary prompt PS2 when it needs more input to complete a command. Bash allows these prompt strings to be customized by inserting a number of backslash-escaped special characters that are decoded as follows:

          \w     the  current working directory, with $HOME
                 abbreviated with a tilde (uses the value of the
                 PROMPT_DIRTRIM variable)
          \W     the basename of the current working directory,
                 with $HOME abbreviated with a tilde

You can include the result for a command - since I don't know git well enough, I use $(date +%S) as example:

PS1='\w $(date +%S) > '

I don't understand requirement 3. Is this a request how to define colors for ls?

Ah - from the question on U&L, I think you're asking for such a thing:

In ~/.bashrc I have an entry:

# enable color support of ls and also add handy aliases
if [ "$TERM" != "dumb" ]; then
    eval "`dircolors -b`"
    alias ls='ls --color=auto'
fi

to use ls per default with --color=auto.

The Windows Git shell, which is really just bash, sets the prompt $PS1 to a long string that includes $(__git_ps1).

__git_ps1 is defined as a function, nearly 100 lines long, that prints the name of the current branch in parentheses.

/etc/profile (which is C:\Program Files (x86)\Git\etc\profile, at least on my system)) invokes /etc/git-completion.bash, which defines the __git_ps1 function, sets $PS1, defines some git-specific completions, among other things.

The git-completion.bash used by Git Bash appears to be based on this.