texinode(Prompt Expansion)(Restricted Shell)(Compatibility)(Top)
chapter(Prompt Expansion)
ifzman(\
sect(Prompt Expansion)
)\
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.
Some escapes take an optional integer argument, which
should appear between the `tt(%)' and the next character of the
sequence.  The following escape sequences are recognized:

startitem()
item(tt(%%))(
A `tt(%)'.
)
item(tt(%RPAR()))(
A `tt(RPAR())'.
)
xitem(tt(%d))
item(tt(%/))(
Present working directory (tt($PWD)).
)
item(tt(%~))(
tt($PWD).
If it 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($HOME), that part is
replaced by a `tt(~)'.
)
xitem(tt(%c))
xitem(tt(%.))
item(tt(%C))(
Trailing component of tt($PWD).
An integer may follow the `tt(%)' to get more than one component.
Unless `tt(%C)' is used, tilde contraction is performed first.
)
xitem(tt(%h))
item(tt(%!))(
Current history event number.
)
item(tt(%L))(
The current value of tt($SHLVL).
)
item(tt(%M))(
The full machine hostname.
)
item(tt(%m))(
The hostname up to the first `tt(.)'.
An integer may follow the `tt(%)' to specify
how many components of the hostname are desired.
)
item(tt(%S) LPAR()tt(%s)RPAR())(
Start (stop) standout mode.
)
item(tt(%U) LPAR()tt(%u)RPAR())(
Start (stop) underline mode.
)
item(tt(%B) LPAR()tt(%b)RPAR())(
Start (stop) boldface mode.
)
xitem(tt(%t))
item(tt(%@))(
Current time of day, in 12-hour, am/pm format.
)
item(tt(%T))(
Current time of day, in 24-hour format.
)
item(tt(%*))(
Current time of day in 24-hour format, with seconds.
)
item(tt(%n))(
tt($USERNAME).
)
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))(
The date in var(yy)tt(-)var(mm)tt(-)var(dd) 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.
)
item(tt(%l))(
The line (tty) the user is logged in on.
)
item(tt(%?))(
The return code 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 no integer means
print as many as there are.
)
item(tt(%E))(
Clears to end of line.
)
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(%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.
)
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.
)
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.  The test character var(x) may be any of the
following:

startsitem()
sxitem(tt(c))
sxitem(tt(.))
sitem(tt(~))(True if the current path, with prefix replacement, has at least var(n) elements.)
sxitem(tt(/))
sitem(tt(C))(True if the current absolute path has at least var(n) elements.)
sitem(tt(t))(True if the time in minutes is equal to var(n).)
sitem(tt(T))(True if the time in hours is equal to var(n).)
sitem(tt(d))(True if the day of the month is equal to var(n).)
sitem(tt(D))(True if the month is equal to var(n) (January = 0).)
sitem(tt(w))(True if the day of the week is equal to var(n) (Sunday = 0).)
sitem(tt(?))(True if the exit status of the last command was var(n).)
sitem(tt(#))(True if the effective uid of the current process is var(n).)
sitem(tt(g))(True if the effective gid of the current process is var(n).)
sitem(tt(L))(True if the tt(SHLVL) parameter is at least var(n).)
sitem(tt(S))(True if the tt(SECONDS) parameter is at least var(n).)
sitem(tt(v))(True if the array tt(psvar) has at least var(n) elements.)
sitem(tt(_))(True if at least var(n) shell constructs were started.)
sitem(tt(!))(True if the shell is running with privileges.)
endsitem()
)
xitem(tt(%<)var(string)tt(<))
xitem(tt(%>)var(string)tt(>))
item(tt(%[)var(xstring)tt(]))(
Specifies truncation behaviour.
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.  If this
integer is zero, or missing, truncation is disabled.  Truncation is
initially disabled.
The var(string) will be displayed in
place of the truncated portion of any string.

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(\)'.
% escapes are em(not) recognised.
If the var(string) is longer than the specified truncation length,
it will appear in full, completely replacing the truncated string.
)
enditem()