PROMPTING
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PROMPTING
When executing interactively,
bash
displays the primary prompt
.SM
PS1
when it is ready to read a command, and the secondary prompt
.SM
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 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
-
\u
-
the username of the current user
-
\v
-
the version of bash\fP (e.g., 2.00)
-
\V
-
the release of bash\fP, version + patchlevel (e.g., 2.00.0)
-
\w
-
the current working directory
-
\W
-
the basename of the current working directory
-
\!
-
the history number of this command
-
\#
-
the command number of this command
-
\$
-
if the effective UID is 0, a
.BR # ,
otherwise a
$
-
\nnn\fP
-
the character corresponding to the octal number nnn\fP
-
\\
-
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
.SM
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
.SM
"SHELL BUILTIN COMMANDS"
below).
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