Info Catalog bash: The Directory Stack bash: Bash Features bash: The Restricted Shell

bash: Controlling the Prompt

 
 6.9 Controlling the Prompt
 ==========================
 
 The value of the variable 'PROMPT_COMMAND' is examined just before Bash
 prints each primary prompt.  If 'PROMPT_COMMAND' is set and has a
 non-null value, then the value is executed just as if it had been typed
 on the command line.
 
    In addition, the following table describes the special characters
 which can appear in the prompt variables 'PS1' to 'PS4':
 
 '\a'
      A bell character.
 '\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 escape character.
 '\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'
      A newline.
 '\r'
      A carriage return.
 '\s'
      The name of the shell, the basename of '$0' (the portion following
      the final slash).
 '\t'
      The time, in 24-hour HH:MM:SS format.
 '\T'
      The time, in 12-hour HH:MM:SS format.
 '\@'
      The time, in 12-hour am/pm format.
 '\A'
      The time, in 24-hour HH:MM format.
 '\u'
      The username of the current user.
 '\v'
      The version of Bash (e.g., 2.00)
 '\V'
      The release of Bash, version + patchlevel (e.g., 2.00.0)
 '\w'
      The current working directory, with '$HOME' abbreviated with a
      tilde (uses the '$PROMPT_DIRTRIM' variable).
 '\W'
      The basename of '$PWD', with '$HOME' abbreviated with a tilde.
 '\!'
      The history number of this command.
 '\#'
      The command number of this command.
 '\$'
      If the effective uid is 0, '#', otherwise '$'.
 '\NNN'
      The character whose ASCII code is the octal value NNN.
 '\\'
      A backslash.
 '\['
      Begin a sequence of non-printing characters.  This could be used to
      embed a terminal control sequence into the prompt.
 '\]'
      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 (Bash History
 Facilities), 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 (Bash Builtins).
 

Info Catalog bash: The Directory Stack bash: Bash Features bash: The Restricted Shell