.. historic nodename: Prompt Expansion

Prompt Expansion
================================================================================

.. _Expansion of Prompt Sequences:
Expansion of Prompt Sequences
--------------------------------------------------------------------------------
.. index:: single: prompt expansion; Command

.. index:: single: expansion, prompt; Command

Prompt sequences undergo a special form of expansion.  This type of expansion
is also available using the ``-P`` option to the ``print`` builtin.

.. index:: single: PROMPT_SUBST, use of; Program

If the ``PROMPT_SUBST`` option is set, the prompt string is first subjected to
:emphasis:`parameter expansion`,
:emphasis:`command substitution` and
:emphasis:`arithmetic expansion`.
See

.. only:: man

    :manpage:`zshexpn(1)`.
    

.. only:: not man

    :ref:`Expansion`.
    

Certain escape sequences may be recognised in the prompt string.

.. index:: single: PROMPT_BANG, use of; Program

If the ``PROMPT_BANG`` option is set, a ``!`` in the prompt is replaced
by the current history event number.  A literal ``!`` may then be
represented as ``!!``.

.. index:: single: PROMPT_PERCENT, use of; Program

If the ``PROMPT_PERCENT`` option is set, certain escape sequences that
start with ``%`` are expanded.
Many escapes (see :zshsectref:`Simple Prompt Escapes <below>`)
are followed by a single character, although some of these
take an optional integer argument that
should appear between the ``%`` and the next character of the
sequence.  More complicated escape sequences
(see :zshsectref:`Conditional Substrings in Prompts <below>`)
are available to provide conditional expansion.

.. _Simple Prompt Escapes:
Simple Prompt Escapes
--------------------------------------------------------------------------------

Special Characters
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

``%%``
    
    A ``%``.
    

``%)``
    
    A ``)``.
    

Login Information
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

``%l``
    
    The line (tty) the user is logged in on, without ``/dev/`` prefix.
    If the name starts with ``/dev/tty``, that prefix is stripped.
    

``%M``
    
    The full machine hostname.
    

``%m``
    
    The hostname up to the first ``.``.
    An integer may follow the ``%`` to specify
    how many components of the hostname are desired.  With a negative integer,
    trailing components of the hostname are shown.
    

``%n``
    
    ``$USERNAME``.
    

``%y``
    
    The line (tty) the user is logged in on, without ``/dev/`` prefix.
    This does not treat ``/dev/tty`` names specially.
    

Shell State
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

``%#``
    
    A ``#`` if the shell is running with privileges, a ``%`` if not.
    Equivalent to ``%(!.#.%%)``.
    The definition of \`privileged', for these purposes, is that either the
    effective user ID is zero, or, if POSIX.1e capabilities are supported, that
    at least one capability is raised in either the Effective or Inheritable
    capability vectors.
    

``%?``
    
    The return status of the last command executed just before the prompt.
    

``%_``
    
    The status of the parser, i.e. the shell constructs (like ``if`` and
    ``for``) that have been started on the command line. If given an integer
    number that many strings will be printed; zero or negative or no integer means
    print as many as there are.  This is most useful in prompts ``PS2`` for
    continuation lines and ``PS4`` for debugging with the ``XTRACE`` option; in
    the latter case it will also work non-interactively.
    

``%^``
    
    The status of the parser in reverse. This is the same as ``%_`` other than
    the order of strings.  It is often used in ``RPS2``.
    

``%d``

``%/``
    
    Current working directory.  If an integer follows the ``%``,
    it specifies a number of trailing components of the current working
    directory to show; zero means the whole path.  A negative integer
    specifies leading components, i.e. ``%-1d`` specifies the first component.
    

``%~``
    
    As ``%d`` and ``%/``, but if the current working directory starts with
    ``$HOME``, that part is replaced by a ``~``. Furthermore, if it has a named
    directory as its prefix, that part is replaced by a ``~`` followed by
    the name of the directory, but only if the result is shorter than
    the full path; see :strong:`Dynamic` and :strong:`Static Named Directories` in
    :zshsectref:`Filename Expansion <zshexpn>`.
    

``%e``
    
    Evaluation depth of the current sourced file, shell function, or ``eval``.
    This is incremented or decremented every time the value of ``%N`` is
    set or reverted to a previous value, respectively.  This is most useful
    for debugging as part of ``$PS4``.
    

``%h``

``%!``
    
    Current history event number.
    

``%i``
    
    The line number currently being executed in the script, sourced file, or
    shell function given by ``%N``.  This is most useful for debugging as part
    of ``$PS4``.
    

``%I``
    
    The line number currently being executed in the file ``%x``.  This is
    similar to ``%i``, but the line number is always a line number in the
    file where the code was defined, even if the code is a shell function.
    

``%j``
    
    The number of jobs.
    

``%L``
    
    The current value of ``$SHLVL``.
    

``%N``
    
    The name of the script, sourced file, or shell function that zsh is
    currently executing, whichever was started most recently.  If there is
    none, this is equivalent to the parameter ``$0``.  An integer may follow
    the ``%`` to specify a number of trailing path components to show; zero
    means the full path.  A negative integer specifies leading components.
    

``%x``
    
    The name of the file containing the source code currently being
    executed.  This behaves as ``%N`` except that function and eval command
    names are not shown, instead the file where they were defined.
    

``%c``

``%.``

``%C``
    
    Trailing component of the current working directory.
    An integer may follow the ``%`` to get more than one component.
    Unless ``%C`` is used, tilde contraction is performed first.  These are
    deprecated as ``%c`` and ``%C`` are equivalent to ``%1~`` and ``%1/``,
    respectively, while explicit positive integers have the same effect as for
    the latter two sequences.
    

Date and Time
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

``%D``
    
    The date in :var:`yy`\ ``-``:var:`mm`\ ``-``:var:`dd` format.
    

``%T``
    
    Current time of day, in 24-hour format.
    

``%t``

``%@``
    
    Current time of day, in 12-hour, am/pm format.
    

``%*``
    
    Current time of day in 24-hour format, with seconds.
    

``%w``
    
    The date in :var:`day`\ ``-``:var:`dd` format.
    

``%W``
    
    The date in :var:`mm`\ ``/``:var:`dd`\ ``/``:var:`yy` format.
    

``%D{``:var:`string`\ ``}``
    
    :var:`string` is formatted using the ``strftime`` function.
    See :manpage:`strftime(3)` for more details.  Various zsh
    extensions provide numbers with no leading zero or space
    if the number is a single digit:
    
    
    ``%f``
        a day of the month
    
    ``%K``
        the hour of the day on the 24-hour clock
    
    ``%L``
        the hour of the day on the 12-hour clock
    
    
    
    In addition, if the system supports the POSIX ``clock_gettime``
    or ``gettimeofday`` system
    call, ``%.`` provides decimal fractions of a second since the epoch with
    leading zeroes.  By default three decimal places are provided, but a
    number of digits up to 9 may be given following the ``%``; hence ``%6.``
    outputs microseconds, and ``%9.`` outputs nanoseconds.  (The latter
    requires a nanosecond-precision ``clock_gettime``; systems lacking this
    will return a value multiplied by the appropriate power of 10.)  A typical
    example of this is the format ``%D{%H:%M:%S.%.}``.
    
    The GNU extension ``%N`` is handled as a synonym for ``%9.``.
    
    Additionally, the GNU extension that a ``-`` between the ``%`` and the
    format character causes a leading zero or space to be stripped
    is handled directly by the shell for the format characters ``d``, ``f``,
    ``H``, ``k``, ``l``, ``m``, ``M``, ``S`` and ``y``; any other format
    characters are provided to the system's strftime(3)
    with any leading ``-`` present, so the handling is system dependent.
    Further GNU (or other) extensions are also passed to strftime(3)
    and may work if the system supports them.
    

Visual Effects
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

``%B`` (``%b``)
    
    Start (stop) boldface mode.
    

``%E``
    
    Clear to end of line.
    

``%U`` (``%u``)
    
    Start (stop) underline mode.
    

``%S`` (``%s``)
    
    Start (stop) standout mode.
    

``%F`` (``%f``)
    
    Start (stop) using a different foreground colour, if supported
    by the terminal.  The colour may be specified two ways: either
    as a numeric argument, as normal, or by a sequence in braces
    following the ``%F``, for example ``%F{red}``.  In the latter case
    the values allowed are as described for the ``fg`` ``zle_highlight``
    attribute; see :zshsectref:`Character Highlighting <zshzle>`.
    This means that numeric
    colours are allowed in the second format also.
    

``%K`` (``%k``)
    
    Start (stop) using a different bacKground colour.  The syntax is
    identical to that for ``%F`` and ``%f``.
    

``%H``
    
    Change all character visual attributes using a highlighting specification from
    the ``.zle.hlgroups`` associative array. The key is specified in following
    braces so, for example ``%H{error}`` will use the highlighting specification
    for the \`error' group.  If the key is not found in the associative array then
    it has no effect.  Highlighting specifications are in the same format as for
    the ``zle_highlight`` parameter.
    If the following braces are absent, attributes are reset to the defaults.
    

``%{...%}``
    
    Include a string as a literal escape sequence.
    The string within the braces should not change the cursor
    position.  Brace pairs can nest.
    
    A positive numeric argument between the ``%`` and the ``{`` is treated as
    described for ``%G`` below.
    

``%G``
    
    Within a ``%{...%}`` sequence, include a \`glitch': that is, assume
    that a single character width will be output.  This is useful when
    outputting characters that otherwise cannot be correctly handled by the
    shell, such as the alternate character set on some terminals.
    The characters in question can be included within a ``%{...%}``
    sequence together with the appropriate number of ``%G`` sequences to
    indicate the correct width.  An integer between the ``%`` and ``G``
    indicates a character width other than one.  Hence ``%{``:var:`seq`\ ``%2G%}``
    outputs :var:`seq` and assumes it takes up the width of two standard
    characters.
    
    Multiple uses of ``%G`` accumulate in the obvious fashion; the position
    of the ``%G`` is unimportant.  Negative integers are not handled.
    
    Note that when prompt truncation is in use it is advisable to divide up
    output into single characters within each ``%{...%}`` group so that
    the correct truncation point can be found.
    

.. _Conditional Substrings in Prompts:
Conditional Substrings in Prompts
--------------------------------------------------------------------------------

``%v``
    
    .. index:: single: psvar, use of; Variable
    
    
    The value of the first element of the ``psvar`` array parameter.  Following
    the ``%`` with an integer gives that element of the array.  Negative
    integers count from the end of the array.
    

``%(``:var:`x`\ ``.``:var:`true-text`\ ``.``:var:`false-text`\ ``)``
    
    Specifies a ternary expression.  The character following the :var:`x` is
    arbitrary; the same character is used to separate the text for the
    \`true' result from that for the \`false' result.
    This separator may not appear in the :var:`true-text`, except as part of a
    %-escape
    sequence.  A ``)`` may appear in the :var:`false-text` as ``%)``.
    :var:`true-text`
    and :var:`false-text` may both contain arbitrarily-nested escape
    sequences, including further ternary expressions.
    
    The left parenthesis may be preceded or followed by a positive integer :var:`n`,
    which defaults to zero.  A negative integer will be multiplied by -1, except
    as noted below for ``l``.
    The test character :var:`x` may be any of the following:
    
    
    ``!``
        True if the shell is running with privileges.
    
    ``#``
        True if the effective uid of the current process is :var:`n`.
    
    ``?``
        True if the exit status of the last command was :var:`n`.
    
    ``_``
        True if at least :var:`n` shell constructs were started.
    
    ``C``
    
    ``/``
        True if the current absolute path has at least :var:`n` elements
        relative to the root directory, hence ``/`` is counted as 0 elements.
    
    ``c``
    
    ``.``
    
    ``~``
        True if the current path, with prefix replacement, has at
        least :var:`n` elements relative to the root directory, hence ``/`` is
        counted as 0 elements.
    
    ``D``
        True if the month is equal to :var:`n` (January = 0).
    
    ``d``
        True if the day of the month is equal to :var:`n`.
    
    ``e``
        True if the evaluation depth is at least :var:`n`.
    
    ``g``
        True if the effective gid of the current process is :var:`n`.
    
    ``j``
        True if the number of jobs is at least :var:`n`.
    
    ``L``
        True if the ``SHLVL`` parameter is at least :var:`n`.
    
    ``l``
        True if at least :var:`n` characters have already been
        printed on the current line.  When :var:`n` is negative, true if at least
        ``abs(``:var:`n`\ ``)`` characters remain before the opposite
        margin (thus the left margin for ``RPROMPT``).
    
    ``S``
        True if the ``SECONDS`` parameter is at least :var:`n`.
    
    ``T``
        True if the time in hours is equal to :var:`n`.
    
    ``t``
        True if the time in minutes is equal to :var:`n`.
    
    ``v``
        True if the array ``psvar`` has at least :var:`n` elements.
    
    ``V``
        True if element :var:`n` of the array ``psvar`` is set and
        non-empty.
    
    ``w``
        True if the day of the week is equal to :var:`n` (Sunday = 0).
    
    
    

``%<``:var:`string`\ ``<``

``%>``:var:`string`\ ``>``

``%[``:var:`xstring`\ ``]``
    
    Specifies truncation behaviour for the remainder of the prompt string.
    The third, deprecated, form is equivalent to ``%``:var:`xstringx`,
    i.e. :var:`x` may be ``<`` or ``>``.
    The :var:`string` will be displayed in
    place of the truncated portion of any string; note this does not
    undergo prompt expansion.
    
    The numeric argument, which in the third form may appear immediately
    after the ``[``, specifies the maximum permitted length of
    the various strings that can be displayed in the prompt.
    In the first two forms, this numeric argument may be negative, in which
    case the truncation length is determined by subtracting the absolute
    value of the numeric argument from the number of character positions
    remaining on the current prompt line.  If this results in a zero or
    negative length, a length of 1 is used.  In other words, a negative
    argument arranges that after truncation at least :var:`n` characters
    remain before the right margin (left margin for ``RPROMPT``).
    
    The forms with ``<`` truncate at the left of the string,
    and the forms with ``>`` truncate at the right of the string.
    For example, if the current directory is ``/home/pike``,
    the prompt ``%8<..<%/`` will expand to ``..e/pike``.
    In this string, the terminating character (``<``, ``>`` or ``]``),
    or in fact any character, may be quoted by a preceding ``\``; note
    when using ``print -P``, however, that this must be doubled as the
    string is also subject to standard ``print`` processing, in addition
    to any backslashes removed by a double quoted string:  the worst case
    is therefore ``print -P "%<\\\\<<..."``.
    
    If the :var:`string` is longer than the specified truncation length,
    it will appear in full, completely replacing the truncated string.
    
    The part of the prompt string to be truncated runs to the end of the
    string, or to the end of the next enclosing group of the ``%(``
    construct, or to the next truncation encountered at the same grouping
    level (i.e. truncations inside a ``%(`` are separate), which
    ever comes first.  In particular, a truncation with argument zero
    (e.g., ``%<<``) marks the end of the range of the string to be
    truncated while turning off truncation from there on. For example, the
    prompt ``%10<...<%~%<<%#``  will print a truncated representation of the
    current directory, followed by a ``%`` or ``#``, followed by a
    space.  Without the ``%<<``, those two characters would be included
    in the string to be truncated.  Note that ``%-0<<`` is not equivalent
    to ``%<<`` but specifies that the prompt is truncated at the right margin.
    
    Truncation applies only within each individual line of the prompt, as
    delimited by embedded newlines (if any).  If the total length of any line
    of the prompt after truncation is greater than the terminal width, or if
    the part to be truncated contains embedded newlines, truncation behavior
    is undefined and may change in a future version of the shell.  Use
    ``%-``:var:`n`\ ``(l.``:var:`true-text`\ ``.``:var:`false-text`\ ``)`` to remove parts
    of the prompt when the available space is less than :var:`n`.
    

