When executing interactively, bash displays the primary prompt PS1 when it is ready to read a command, and the secondary prompt PS2 when it needs more input to complete a command. Bash allows these prompt strings to be customized by inserting a number of backslash-escaped special characters that are decoded as follows:
\a an ASCII bell character (07)
\d the date in “Weekday Month Date” format
(e.g., “Tue May 26”)
\e an ASCII escape character (033)
\h the host name up to the first “.”
\H the host name
\n new line
\r carriage return
\s the name of the shell, the base name of $0
(the portion following the final slash)
\t the current time in 24-hour HH:MM:SS format
\T the current time in 12-hour HH:MM:SS format
\@ the current time in 12-hour AM/PM format
\u the user name of the current user
\v the version of Bash (e.g., 2.00)
\V the release of Bash, version + patch level
(e.g., 2.00.0)
\w the current working directory
\W the base name of the current working directory
\! the history number of this command
\# the command number of this command
\$ if the effective UID is 0, a #; otherwise, a $
\nnn the character corresponding to the octal
number nnn
\\ a backslash
\[ begin a sequence of non-printing characters,
which could be used to embed a terminal control
sequence into the prompt
\] end a sequence of non-printing characters