Proper place to put shell prompt(PS1) when use sh/bash/zsh together

Question

I'm using dash(sh) or bash or zsh. If possible, I would prefer to put in common place.

I want to put proper PS1 settings when I interactive with shell, so these situation should be considered

1. login (show PS1)
2. su
3. sudo
4. script (Don't show PS1)

I was put PS1 on .bashrc, but it seems not always workable.

Answer 1

If you want the same prompt for all shells and users, then put it in the /etc/profile file. It is sourced by all shells, and is the standard place for defining PS1.

Answer 2

Each shell has its own escape sequences for PS1, so you need to set it separately for each shell. Furthermore, PS1 only makes sense for interactive shells, it isn't used by other programs. So put PS1 in the interactive startup file for your shell:

• ~/.bashrc for bash
• ~/.kshrc for ksh
• ~/.zshrc for zsh

Bash has a quirk: it doesn't load .bashrc in a login shell, it only loads ~/.bash_profile or absent this ~/.profile. To fix this, put the following lines in your ~/.bash_profike:

if [ -e ~/.profile ]; then . ~/.profile; fi
case $- in *i*) . ~/.bashrc;; esac

For more information about shell setup files, see Alternative to .bashrc.