gNU Bourne-Again SHell (GNU Bourne-Again SHell)
PROMPTING
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
displays PS0 after it reads a command but before executing it.
Bash displays PS4 as described above before tracing each command
when the -x option is enabled. 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")
\D{format}
the format is passed to strftime(3) and the result
is inserted into the prompt string; an empty format
results in a locale-specific time representation.
The braces are required
\e an ASCII escape character (033)
\h the hostname up to the first `.'
\H the hostname
\j the number of jobs currently managed by the shell
\l the basename of the shell's terminal device name
\n newline
\r carriage return
\s the name of the shell, the basename 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
\A the current time in 24-hour HH:MM format
\u the username 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, with $HOME
abbreviated with a tilde (uses the value of the
PROMPT_DIRTRIM variable)
\W the basename of the current working directory, with
$HOME abbreviated with a tilde
\! 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
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
(see HISTORY below), while the command number is the position in
the sequence of commands executed during the current shell
session. 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 (see the description of the shopt command under SHELL
BUILTIN COMMANDS below). This can have unwanted side effects if
escaped portions of the string appear within command substitution
or contain characters special to word expansion.
