texinode(Prompt Expansion)(Expansion)(Conditional Expressions)(Top)
chapter(Prompt Expansion)
sect(Expansion of Prompt Sequences)
cindex(prompt expansion)
cindex(expansion, prompt)
Prompt sequences undergo a special form of expansion.  This type of expansion
is also available using the tt(-P) option to the tt(print) builtin.

pindex(PROMPT_SUBST, use of)
If the tt(PROMPT_SUBST) option is set, the prompt string is first subjected to
em(parameter expansion),
em(command substitution) and
em(arithmetic expansion).
See
ifzman(\
zmanref(zshexpn).
)\
ifnzman(\
noderef(Expansion).
)\

Certain escape sequences may be recognised in the prompt string.

pindex(PROMPT_BANG, use of)
If the tt(PROMPT_BANG) option is set, a `tt(!)' in the prompt is replaced
by the current history event number.  A literal `tt(!)' may then be
represented as `tt(!!)'.

pindex(PROMPT_PERCENT, use of)
If the tt(PROMPT_PERCENT) option is set, certain escape sequences that
start with `tt(%)' are expanded.
Many escapes are followed by a single character, although some of these
take an optional integer argument that
should appear between the `tt(%)' and the next character of the
sequence.  More complicated escape sequences are available to provide
conditional expansion.

sect(Simple Prompt Escapes)

subsect(Special characters)
startitem()
item(tt(%%))(
A `tt(%)'.
)
item(tt(%RPAR()))(
A `tt(RPAR())'.
)
enditem()

subsect(Login information)
startitem()
item(tt(%l))(
The line (tty) the user is logged in on, without `tt(/dev/)' prefix.
If the name starts with `tt(/dev/tty)', that prefix is stripped.
)
item(tt(%M))(
The full machine hostname.
)
item(tt(%m))(
The hostname up to the first `tt(.)'.
An integer may follow the `tt(%)' to specify
how many components of the hostname are desired.  With a negative integer,
trailing components of the hostname are shown.
)
item(tt(%n))(
tt($USERNAME).
)
item(tt(%y))(
The line (tty) the user is logged in on, without `tt(/dev/)' prefix.
This does not treat `tt(/dev/tty)' names specially.
)
enditem()

subsect(Shell state)
startitem()
item(tt(%#))(
A `tt(#)' if the shell is running with privileges, a `tt(%)' if not.
Equivalent to `tt(%(!.#.%%))'.
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.
)
item(tt(%?))(
The return status of the last command executed just before the prompt.
)
item(tt(%_))(
The status of the parser, i.e. the shell constructs (like `tt(if)' and
`tt(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 tt(PS2) for
continuation lines and tt(PS4) for debugging with the tt(XTRACE) option; in
the latter case it will also work non-interactively.
)
xitem(tt(%d))
item(tt(/))(
Current working directory.  If an integer follows the `tt(%)',
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. tt(%-1d) specifies the first component.
)
item(tt(%~))(
As tt(%d) and tt(%/), but if the current working directory starts with
tt($HOME), that part is replaced by a `tt(~)'. Furthermore, if it has a named
directory as its prefix, that part is replaced by a `tt(~)' followed by
the name of the directory, but only if the result is shorter than
the full path; 
ifzman(see em(Dynamic) and em(Static named directories) in zmanref(zshexpn))\
ifnzman(noderef(Filename Expansion)).
)
xitem(tt(%h))
item(tt(%!))(
Current history event number.
)
item(tt(%i))(
The line number currently being executed in the script, sourced file, or
shell function given by tt(%N).  This is most useful for debugging as part
of tt($PS4).
)
item(tt(%I))(
The line number currently being executed in the file tt(%x).  This is
similar to tt(%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.
)
item(tt(%j))(
The number of jobs.
)
item(tt(%L))(
The current value of tt($SHLVL).
)
item(tt(%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 tt($0).  An integer may follow
the `tt(%)' to specify a number of trailing path components to show; zero
means the full path.  A negative integer specifies leading components.
)
item(tt(%x))(
The name of the file containing the source code currently being
executed.  This behaves as tt(%N) except that function and eval command
names are not shown, instead the file where they were defined.
)
xitem(tt(%c))
xitem(tt(%.))
item(tt(%C))(
Trailing component of the current working directory.
An integer may follow the `tt(%)' to get more than one component.
Unless `tt(%C)' is used, tilde contraction is performed first.  These are
deprecated as tt(%c) and tt(%C) are equivalent to tt(%1~) and tt(%1/),
respectively, while explicit positive integers have the same effect as for
the latter two sequences.
)
enditem()

subsect(Date and time)
startitem()
item(tt(%D))(
The date in var(yy)tt(-)var(mm)tt(-)var(dd) format.
)
item(tt(%T))(
Current time of day, in 24-hour format.
)
xitem(tt(%t))
item(tt(%@))(
Current time of day, in 12-hour, am/pm format.
)
item(tt(%*))(
Current time of day in 24-hour format, with seconds.
)
item(tt(%w))(
The date in var(day)tt(-)var(dd) format.
)
item(tt(%W))(
The date in var(mm)tt(/)var(dd)tt(/)var(yy) format.
)
item(tt(%D{)var(string)tt(}))(
var(string) is formatted using the tt(strftime) function.
See manref(strftime)(3) for more details.  Various zsh
extensions provide numbers with no leading zero or space
if the number is a single digit:

startsitem()
sitem(tt(%f))(a day of the month)
sitem(tt(%K))(the hour of the day on the 24-hour clock)
sitem(tt(%L))(the hour of the day on the 12-hour clock)
endsitem()

In addition, if the system supports the POSIX tt(gettimeofday) system
call, tt(%.) 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 6 may be given following the tt(%); hence tt(%6.)
outputs microseconds.  A typical example of this is the format
`tt(%D{%H:%M:%S.%.})'.

The GNU extension that a `tt(-)' between the tt(%) and the
format character causes a leading zero or space to be stripped
is handled directly by the shell for the format characters tt(d), tt(f),
tt(H), tt(k), tt(l), tt(m), tt(M), tt(S) and tt(y); any other format
characters are provided to tt(strftime+LPAR()RPAR()) with any leading `tt(-)',
present, so the handling is system dependent.  Further GNU
extensions are not supported at present.
)
enditem()

subsect(Visual effects)
startitem()
item(tt(%B) LPAR()tt(%b)RPAR())(
Start (stop) boldface mode.
)
item(tt(%E))(
Clear to end of line.
)
item(tt(%U) LPAR()tt(%u)RPAR())(
Start (stop) underline mode.
)
item(tt(%S) LPAR()tt(%s)RPAR())(
Start (stop) standout mode.
)
item(tt(%F) LPAR()tt(%f)RPAR())(
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 tt(%F), for example tt(%F{red}).  In the latter case
the values allowed are as described for the tt(fg) tt(zle_highlight)
attribute;
ifzman(see em(Character Highlighting) in zmanref(zshzle))\
ifnzman(noderef(Character Highlighting)).  This means that numeric
colours are allowed in the second format also.
)
item(tt(%K) LPAR()tt(%k)RPAR())(
Start (stop) using a different bacKground colour.  The syntax is
identical to that for tt(%F) and tt(%f).
)
item(tt(%{)...tt(%}))(
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 tt(%) and the tt({) is treated as
described for tt(%G) below.
)
item(tt(%G))(
Within a tt(%{)...tt(%}) 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 tt(%{)...tt(%})
sequence together with the appropriate number of tt(%G) sequences to
indicate the correct width.  An integer between the `tt(%)' and `tt(G)'
indicates a character width other than one.  Hence tt(%{)var(seq)tt(%2G%})
outputs var(seq) and assumes it takes up the width of two standard
characters.

Multiple uses of tt(%G) accumulate in the obvious fashion; the position
of the tt(%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 tt(%{)...tt(%}) group so that
the correct truncation point can be found.
)
enditem()

sect(Conditional Substrings in Prompts)
startitem()
item(tt(%v))(
vindex(psvar, use of)
The value of the first element of the tt(psvar) array parameter.  Following
the `tt(%)' with an integer gives that element of the array.  Negative
integers count from the end of the array.
)
item(tt(%LPAR())var(x.true-text.false-text)tt(RPAR()))(
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 `tt(RPAR())' may appear in the var(false-text) as `tt(%RPAR())'.
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 `tt(l)'.
The test character var(x) may be any of the following:

startsitem()
sitem(tt(!))(True if the shell is running with privileges.)
sitem(tt(#))(True if the effective uid of the current process is var(n).)
sitem(tt(?))(True if the exit status of the last command was var(n).)
sitem(tt(_))(True if at least var(n) shell constructs were started.)
sxitem(tt(C))
sitem(tt(/))(True if the current absolute path has at least var(n) elements
relative to the root directory, hence tt(/) is counted as 0 elements.)
sxitem(tt(c))
sxitem(tt(.))
sitem(tt(~))(True if the current path, with prefix replacement, has at
least var(n) elements relative to the root directory, hence tt(/) is
counted as 0 elements.)
sitem(tt(D))(True if the month is equal to var(n) (January = 0).)
sitem(tt(d))(True if the day of the month is equal to var(n).)
sitem(tt(g))(True if the effective gid of the current process is var(n).)
sitem(tt(j))(True if the number of jobs is at least var(n).)
sitem(tt(L))(True if the tt(SHLVL) parameter is at least var(n).)
sitem(tt(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
tt(abs)tt(LPAR())var(n)tt(RPAR()) characters remain before the opposite
margin (thus the left margin for tt(RPROMPT)).)
sitem(tt(S))(True if the tt(SECONDS) parameter is at least var(n).)
sitem(tt(T))(True if the time in hours is equal to var(n).)
sitem(tt(t))(True if the time in minutes is equal to var(n).)
sitem(tt(v))(True if the array tt(psvar) has at least var(n) elements.)
sitem(tt(V))(True if element var(n) of the array tt(psvar) is set and
non-empty.)
sitem(tt(w))(True if the day of the week is equal to var(n) (Sunday = 0).)
endsitem()
)
xitem(tt(%<)var(string)tt(<))
xitem(tt(%>)var(string)tt(>))
item(tt(%[)var(xstring)tt(]))(
Specifies truncation behaviour for the remainder of the prompt string.
The third, deprecated, form is equivalent to `tt(%)var(xstringx)',
i.e. var(x) may be `tt(<)' or `tt(>)'.
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 `tt([)', 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 tt(RPROMPT)).

The forms with `tt(<)' truncate at the left of the string,
and the forms with `tt(>)' truncate at the right of the string.
For example, if the current directory is `tt(/home/pike)',
the prompt `tt(%8<..<%/)' will expand to `tt(..e/pike)'.
In this string, the terminating character (`tt(<)', `tt(>)' or `tt(])'),
or in fact any character, may be quoted by a preceding `tt(\)'; note
when using tt(print -P), however, that this must be doubled as the
string is also subject to standard tt(print) processing, in addition
to any backslashes removed by a double quoted string:  the worst case
is therefore `tt(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 `tt(%LPAR())'
construct, or to the next truncation encountered at the same grouping
level (i.e. truncations inside a `tt(%LPAR())' are separate), which
ever comes first.  In particular, a truncation with argument zero
(e.g., `tt(%<<)') 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 `tt(%)' or `tt(#)', followed by a
space.  Without the `tt(%<<)', those two characters would be included
in the string to be truncated.  Note that `tt(%-0<<)' is a distinct

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
`tt(%-var(n)LPAR()l.var(true-text).var(false-text)RPAR())' to remove parts
of the prompt when the available space is less than var(n).
)
enditem()
