Prompt Statement variables

There are several variables that can be set to control the appearance of the bach 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 file.

Special characters which can appear in prompt variables:

\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. 
\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.

Examples

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

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.

PS1='\[\e[33m\]MyFancyPrompt\[\e[0m\] '

Set a prompt thats glued to the first column (via Joni Salonen)

PS1="\[\033[G\]$PS1"

Notes

The command number and the history number are usually different: the history number of a command is its position in the history list, which may include commands restored from the history file, while the command number is the position in the sequence of commands executed.

After the string is decoded, it is expanded via parameter expansion, command substitution, arithmetic expansion, and quote removal, subject to the value of the promptvars shell option.

Related commands:

env - Display, set, or remove environment variables
export
- Set an environment variable
Bash Prompt HowTo
bashish.sourceforge.net - Color the terminal prompt without affecting the enviroment.
Windows equivalent command: PROMPT - Change the command prompt


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