Skip to content

Latest commit

 

History

History
117 lines (82 loc) · 3.48 KB

prompt-statement-variables.md

File metadata and controls

117 lines (82 loc) · 3.48 KB
Raw

Bash Shell Prompt Statement Variables

Source: https://ss64.com/bash/syntax-prompt.html

There are several variables that can be set to control the appearance of the bash command prompt: PS1, PS2, PS3, PS4 and PROMPT_COMMAND the contents are executed just as if they had been typed on the command line.

  • PS1 – Default interactive prompt (this is the variable most often customized)
  • PS2 – Continuation interactive prompt (when a long command is broken up with \ at the end of the line) default=">"
  • PS3 – Prompt used by select loop inside a shell script
  • PS4 – Prompt used when a shell script is executed in debug mode (set -x will turn this on) default ="++"
  • PROMPT_COMMAND - If this variable is set and has a non-null value, then it will be executed just before the PS1 variable.

Set your prompt by changing the value of the PS1 environment variable, as follows:

$ export PS1="My simple prompt> "
>

This change can be made permanent by placing the export definition in your ~/.bashrc (or ~/.bash_profile) file.

Special prompt variable characters

 \d   The date, in "Weekday Month Date" format (e.g., "Tue May 26").

 \h   The hostname, up to the first . (e.g. deckard)
 \H   The hostname. (e.g. deckard.SS64.com)

 \j   The number of jobs currently managed by the shell.

 \l   The basename of the shell's terminal device name.

 \s   The name of the shell, the basename of $0 (the portion following
      the final slash).

 \t   The time, in 24-hour HH:MM:SS format.
 \T   The time, in 12-hour HH:MM:SS format.
 \@   The time, in 12-hour am/pm format.

 \u   The username of the current user.

 \v   The version of Bash (e.g., 2.00)

 \V   The release of Bash, version + patchlevel (e.g., 2.00.0)

 \w   The current working directory.
 \W   The basename of $PWD.

 \!   The history number of this command.
 \#   The command number of this command.

 \$   If you are not root, inserts a "$"; if you are root, you get a "#"  (root uid = 0)

 \nnn   The character whose ASCII code is the octal value nnn.

 \n   A newline.
 \r   A carriage return.
 \e   An escape character (typically a color code).
 \a   A bell character.
 \\   A backslash.

 \[   Begin a sequence of non-printing characters. (like color escape sequences). This
      allows bash to calculate word wrapping correctly.

 \]   End a sequence of non-printing characters.

Using single quotes instead of double quotes when exporting your PS variables is recommended, it makes the prompt a tiny bit faster to evaluate plus you can then do an echo $PS1 to see the current prompt settings.

Color Codes (ANSI Escape Sequences)

Foreground colors

Normal (non-bold) is the default, so the 0; prefix is optional.

\e[0;30m = Dark Gray
\e[1;30m = Bold Dark Gray
\e[0;31m = Red
\e[1;31m = Bold Red
\e[0;32m = Green
\e[1;32m = Bold Green
\e[0;33m = Yellow
\e[1;33m = Bold Yellow
\e[0;34m = Blue
\e[1;34m = Bold Blue
\e[0;35m = Purple
\e[1;35m = Bold Purple
\e[0;36m = Turquoise
\e[1;36m = Bold Turquoise
\e[0;37m = Light Gray
\e[1;37m = Bold Light Gray

Background colors

\e[40m = Dark Gray
\e[41m = Red
\e[42m = Green
\e[43m = Yellow
\e[44m = Blue
\e[45m = Purple
\e[46m = Turquoise
\e[47m = Light Gray

Examples

Set a prompt like: [username@hostname:~/CurrentWorkingDirectory]$

export PS1='[\u@\h:\w]\$ '

Set a prompt in color. Note the escapes for the non printing characters [ ]. These ensure that readline can keep track of the cursor position correctly.

export PS1='\[\e[31m\]\u@\h:\w\[\e[0m\] '