(zsh.info.gz) Prompt Expansion
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13 Prompt Expansion
*******************
13.1 Expansion of Prompt Sequences
==================================
Prompt sequences undergo a special form of expansion. This type of
expansion is also available using the -P option to the print builtin.
If the PROMPT_SUBST option is set, the prompt string is first subjected
to _parameter expansion_, _command substitution_ and _arithmetic
expansion_. See Expansion.
Certain escape sequences may be recognised in the prompt string.
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
'!!'.
If the PROMPT_PERCENT option is set, certain escape sequences that start
with '%' are expanded. Many escapes 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 are available to provide conditional
expansion.
13.2 Simple Prompt Escapes
==========================
13.2.1 Special characters
-------------------------
%%
A '%'.
%)
A ')'.
13.2.2 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.
13.2.3 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.
%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 has a named
directory as its prefix, that part is replaced by a '~' followed by
the name of the directory. If it starts with $HOME, that part is
replaced by a '~'.
%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.
13.2.4 Date and time
--------------------
%D
The date in YY-MM-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 DAY-DD format.
%W
The date in MM/DD/YY format.
%D{STRING}
STRING is formatted using the strftime function. See man page
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
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 strftime() with any
leading '-', present, so the handling is system dependent. Further
GNU extensions are not supported at present.
13.2.5 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;
Character Highlighting. 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.
%{...%}
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 %{SEQ%2G%}
outputs 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.
13.3 Conditional Substrings in Prompts
======================================
%v
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.
%(X.TRUE-TEXT.FALSE-TEXT)
Specifies a ternary expression. The character following the 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 TRUE-TEXT, except as part of a %-escape sequence.
A ')' may appear in the FALSE-TEXT as '%)'. TRUE-TEXT and
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 N, which defaults to zero. A negative integer will be
multiplied by -1. The test character 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 N.
?
True if the exit status of the last command was N.
_
True if at least N shell constructs were started.
C
/
True if the current absolute path has at least 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 N elements relative to the root directory, hence / is
counted as 0 elements.
D
True if the month is equal to N (January = 0).
d
True if the day of the month is equal to N.
g
True if the effective gid of the current process is N.
j
True if the number of jobs is at least N.
L
True if the SHLVL parameter is at least N.
l
True if at least N characters have already been printed on the
current line.
S
True if the SECONDS parameter is at least N.
T
True if the time in hours is equal to N.
t
True if the time in minutes is equal to N.
v
True if the array psvar has at least N elements.
V
True if element N of the array psvar is set and non-empty.
w
True if the day of the week is equal to N (Sunday = 0).
%<STRING<
%>STRING>
%[XSTRING]
Specifies truncation behaviour for the remainder of the prompt
string. The third, deprecated, form is equivalent to '%XSTRINGX',
i.e. X may be '<' or '>'. 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. The STRING will be displayed in place of
the truncated portion of any string; note this does not undergo
prompt expansion.
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 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.
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