Make a fish-style command prompt

[davclark]

This makes it easier to see what's being typed. Dav has an example - just ask him.

[aculich]

@davclark upload your .rc file and show us screenshots, please!

[cboettig]

:+1:

[davclark]

Sorry this has fallen so far to the wayside...

I had been keeping prompt customizations in .profile, but it turns out byobu wants such things in .bashrc. Thanks for "prompting" that investigation.

The secret sauce is something like this:

# We separate this into two lines to make things easier to read                 
fish_style_dir_cmd='CurDir=`pwd|sed -e "s!$HOME!~!"|sed -Ee "s!([^/])[^/]+/!\1/!g"`'                                                                            
export PROMPT_COMMAND="$fish_style_dir_cmd; $PROMPT_COMMAND"  

Then you put $CurDir instead of \w for the prompt, like so:

if [ "$color_prompt" = yes ]; then                                              
    # PS1="${win_title}\u@\h \$CurDir$bold\$$plain "                            
    PS1='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[00m\]:\[\033[01;34m\]$CurDir\[\033[00m\]\$ '                                              
else                                                                            
    PS1='${debian_chroot:+($debian_chroot)}\u@\h:$CurDir\$ '                    
fi                                                                              
unset color_prompt force_color_prompt

Be careful of Bash escaping rules :footprints: :gun:

In my OS X prompt, I have a much more interpretable looking thing like this:

bold="\[\e[1m\]"
plain="\[\e[0m\]"
win_title='\[\033]0;\u@\h: \w\007\]'
# The $ is escaped before CurDir because we want it evaluated for each prompt
PS1="${win_title}dav@$(networksetup -getcomputername) \$CurDir$bold\$$plain "

That's way easier to interpret, and would be a good style for BCE. However I simply don't feel like even thinking about the escaping above to clarify things. E.g., "does \[\033[01;34m\] == $bold? Looks like some extra 34 in there... Does that do anything? Oops, times up!"

I also have to say that the default oh-my-zsh / bash-it prompt may be better for our students as a prompt (but even less comprehensible). It uses unicode to make a very clear 2-line prompt in the modern theme. Here is a super-simple version inspired by that (using $plain and $bold from above):

PS1="┌─\u@\h:${bold}\w${plain}\n└─\$ "