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(%/))(
Present working directory (tt($PWD)).  If an integer follows the `tt(%)',
it specifies a number of trailing components of tt($PWD) 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 tt($PWD) has a named directory as its prefix,
that part is replaced by a `tt(~)' followed by the name of the directory.
If it starts with tt($HOME), that part is replaced by a `tt(~)'.
)
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($PS4).
)
item(tt(%j))(
The number of jobs.
)
item(tt(%L))(
The current value of tt($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($0).  An integer may follow
the `tt(%)' to specify a number of trailing path components to show; zero
means the full path.  A negative integer specifies leading components.
)
xitem(tt(%c))
xitem(tt(%.))
item(tt(%C))(
Trailing component of tt($PWD).
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.  Three additional codes are
available:  tt(%f) prints the day of the month, like tt(%e) but
without any preceding space if the day is a single digit, and
tt(%K)/tt(%L) correspond to tt(%k)/tt(%l) for the hour of the day
(24/12 hour clock) in the same way.
)
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(%{)...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 %%({) 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.
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.)
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(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 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.
The var(string) will be displayed in
place of the truncated portion of any string; note this does not
undergo prompt expansion.

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.
)
enditem()
