How to customize the Bash prompt

A Bash prompt should show enough context to keep commands in the right directory and on the right host. The PS1 variable controls that prompt, so a small change can show the user, host, working directory, and a visual marker before each command.

Bash expands prompt escape sequences such as \u, \h, \w, and \$ each time it draws the prompt. Color sequences also work, but nonprinting terminal codes need \[ and \] markers so command-line editing keeps the cursor position aligned.

A temporary assignment is safest for testing because it affects only the current shell. A persistent prompt belongs in ~/.bashrc for interactive Bash sessions, after any existing PS1 assignment that would otherwise override it.

1. Set a temporary prompt for the current shell.

   $ PS1='[work] \u@\h:\w\$ '
   [work] user@host:~$

   \u shows the user, \h shows the short host name, \w shows the working directory, and \$ changes to # when the shell is running as root.

2. Test a colored prompt with nonprinting escape markers.

   $ PS1='\[\e[1;32m\][work]\[\e[0m\] \u@\h:\w\$ '
   [work] user@host:~$

   The \e[1;32m sequence starts bold green text, and \e[0m resets the terminal style.

3. Start a new Bash shell to discard the temporary prompt.

   $ exec bash

   This replaces the current shell and reloads the normal startup files.

1. Back up the Bash startup file.

   $ cp ~/.bashrc ~/.bashrc.bak

   A broken startup file can make new interactive shells hard to use until the prompt line is fixed or removed.

2. Open ~/.bashrc in a text editor.

   $ nano ~/.bashrc

3. Add the prompt assignment near the end of the file.

   PS1='\[\e[1;36m\]\u@\h:\w\$\[\e[0m\] '

   Place the line after any existing PS1 assignment so the new value is the one Bash keeps.

4. Save the file and close the editor.
5. Check the edited startup file for Bash syntax errors.

   $ bash -n ~/.bashrc

   No output means Bash parsed the file without finding a syntax error.

6. Load the updated Bash startup file.

   $ source ~/.bashrc

7. Confirm a new interactive Bash shell reads the saved prompt string.

   $ bash --noprofile --rcfile ~/.bashrc -i -c 'printf "%s\n" "$PS1"' 2>/dev/null
   \[\e[1;36m\]\u@\h:\w\$\[\e[0m\] 

   This verification starts Bash with the saved startup file and prints the raw PS1 value instead of drawing a full interactive prompt.