Linux shell/Bash prompt PS1, settings and history

This are steps to set up bash prompt showing git branch. This has been tested in Ubuntu 14 LTS

Edit vi ~/.bashrc

1. Uncomment #force_color_prompt=yes
2. Find if [ "$color_prompt" = yes ]; then statement
3. then comment out #PS1= and add following code in bold

if [ "$color_prompt" = yes ]; then
        parse_git_branch() {
        git branch 2> /dev/null | sed -e '/^[^*]/d' -e 's/* \(.*\)/ (\1)/'
        }
        PS1="\u@\h \[\033[32m\]\w\[\033[33m\]\$(parse_git_branch)\[\033[00m\] $ "
       #PS1='${debian_chroot:+($debian_chroot)}\[\033[01;32m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\w\[\033[00m\]\$ ' #this is default colour prompt
else
    PS1='${debian_chroot:+($debian_chroot)}\u@\h:\w\$ '
fi

It will similar to

Reload shell without logging out

. ~/.bashrc
source ~/.bashrc
exec bash
exec "$BASH"

Differences

• source ~/.bashrc will preserve your current shell. Except for the modifications that reloading ~/.bashrc into the current shell (sourcing) makes, the current shell and its state are preserved, which includes environment variables, shell variables, shell options, shell functions, and command history.
• exec bash, or, more robustly, exec "$BASH"[1], will replace your current shell with a new instance, and therefore only preserve your current shell's environment variables (including ones you've defined ad-hoc). In other words: Any ad-hoc changes to the current shell in terms of shell variables, shell functions, shell options, command history are lost.

[1] exec bash could in theory execute a different bash executable than the one that started the current shell, if it happens to exist in a directory listed earlier in the $PATH. Since special variable $BASH always contains the full path of the executable that started the current shell, exec "$BASH" is guaranteed to use the same executable.

Resources

• CustomizingBashPrompt Ubuntu wiki
• Git Bash Prompt repo project Great informative Git prompt