bash-prompt.md

Bash Prompt Customization

• Prompts:
  • PS1: Default interactive
  • PS2: Continuation interactive
  • PS3: Select (builtin)
  • PS4: set -x uses this to prefix tracing output

| Prompt | Description | Example | Result |

| \a | ASCII bell character (07) | \a$ $ | (and beep) | \d | Date in “Weekday Month Date” format | \d$ | Wed Mar 08$ | \e | ASCII escape character (033 | | \h | Hostname up to the first `.’ | \h$ | beebo$ | \H | Hostname | \H$ | beebo.example.com$ | \j | Number of jobs currently managed by the shell | \j$ | 0$ | \l | Basename of the shell’s terminal device name | \l$ | 1$ | \n | Newline | \d\n\h$ | Wed Mar 08 beebo$ | \r | Carriage return | \d\r\h$ | beebo$r 08 | \s | Shell name, basename of $0 (portion following final slash) | \s$ | bash$ | \t | Current time in 24-hour HH:MM:SS format | \t$ | 07:24:57$ | \T | Current time in 12-hour HH:MM:SS format | \T$ | 07:24:57$ | @ | Current time in 12-hour am/pm format | @$ | 07:25 AM$ | \u | Username of the current user | \u$ | david$ | \v | Version of bash (e.g., 2.00) | \v$ | 3.1$ | \V | Release of bash, version + patchlevel (e.g., 2.00.0) | \V$ | 3.1.5$ | \w | Current working directory | \w$ | ~/articles/bash-prompts$ | \W | Basename of the current working directory | \W$ | bash-prompts$ | ! | History number of this command | !$ | 537$ | # | Command number of this command | #$ | 40$ | $ | If the effective UID is 0, a #, otherwise a $ | $ | $ or # as root | \nnn | Character corresponding to the octal number nnn | \141$ | a$ | \ | Backslash | \$ | $ | [ | Begin non-printing character sequence; to embed control sequence into prompt, for example | ] | End non-printing character sequence

Colour: try something like the following:

STARTCOLOUR='\e[31m';
ENDCOLOR="\e[0m"
PS1="$STARTCOLOUR\h \u% $ENDCOLOR"

Or, if you want to not have weird breaks, and change the colours if you're root (for safety), maybe something like this:

case $(id -u) in
    0)
        STARTCOLOUR='\[\e[36m\]';
        ;;
    *)
        STARTCOLOUR='\[\e[31m\]';
        ;;
esac
ENDCOLOR="\[\e[0m\]"
PS1="$STARTCOLOUR\h \u% $ENDCOLOR";

Changing the (xterm) title dynamically:

case $(id -u) in
    0)
        STARTCOLOUR='\[\e[36m\]';
        ;;
    *)
        STARTCOLOUR='\[\e[31m\]';
        ;;
esac
ENDCOLOR="\[\e[0m\]"
case $TERM in
    xterm*)
        TITLEBAR='\[\e]0;\h \w\007\]';
        ;;
    *)
        TITLEBAR="";
        ;;
esac

PS1="$TITLEBAR$STARTCOLOUR\h \u% $ENDCOLOR"