-.\" $NetBSD: printf.1,v 1.10 1998/08/22 14:54:48 garbled Exp $
-.\"
.\" Copyright (c) 1989, 1990, 1993
.\" The Regents of the University of California. All rights reserved.
.\"
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
-.\" 3. All advertising materials mentioning features or use of this software
-.\" must display the following acknowledgement:
-.\" This product includes software developed by the University of
-.\" California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\" may be used to endorse or promote products derived from this software
.\" without specific prior written permission.
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
-.\" from: @(#)printf.1 8.1 (Berkeley) 6/6/93
+.\" @(#)printf.1 8.1 (Berkeley) 6/6/93
+.\" $FreeBSD$
.\"
-.Dd November 5, 1993
+.Dd April 21, 2014
.Dt PRINTF 1
.Os
.Sh NAME
.Nd formatted output
.Sh SYNOPSIS
.Nm
-.Ar format
-.Op Ar arguments ...
+.Ar format Op Ar arguments ...
.Sh DESCRIPTION
+The
.Nm
-formats and prints its arguments, after the first, under control
+utility formats and prints its arguments, after the first, under control
of the
-.Ar format .
+.Ar format .
The
.Ar format
is a character string which contains three types of objects: plain characters,
which are simply copied to standard output, character escape sequences which
are converted and copied to the standard output, and format specifications,
each of which causes printing of the next successive
-.Ar argument .
+.Ar argument .
.Pp
The
.Ar arguments
after the first are treated as strings if the corresponding format is
either
-.Cm b ,
-.Cm c
+.Cm c , b
or
.Cm s ;
otherwise it is evaluated as a C constant, with the following extensions:
.It
A leading plus or minus sign is allowed.
.It
-If the leading character is a single or double quote, the value is the
-.Tn ASCII
-code of the next character.
+If the leading character is a single or double quote, the value is the
+character code of the next character.
.El
.Pp
The format string is reused as often as necessary to satisfy the
-.Ar arguments .
+.Ar arguments .
Any extra format specifications are evaluated with zero or the null
string.
.Pp
-Character escape sequences are in backslash notation as defined in
-.St -ansiC .
+Character escape sequences are in backslash notation as defined in the
+.St -ansiC ,
+with extensions.
The characters and their meanings
are as follows:
-.Bl -tag -width Ds -offset indent
-.It Cm \ee
-Write an <escape> character.
+.Pp
+.Bl -tag -width Ds -offset indent -compact
.It Cm \ea
Write a <bell> character.
.It Cm \eb
Write a <backspace> character.
+.It Cm \ec
+Ignore remaining characters in this string.
.It Cm \ef
Write a <form-feed> character.
.It Cm \en
Write a <single quote> character.
.It Cm \e\e
Write a backslash character.
-.It Cm \e Ns Ar num
-Write an 8-bit character whose
-.Tn ASCII
+.It Cm \e Ns Ar num
+Write a byte whose
value is the 1-, 2-, or 3-digit
octal number
.Ar num .
+Multibyte characters can be constructed using multiple
+.Cm \e Ns Ar num
+sequences.
.El
.Pp
Each format specification is introduced by the percent character
.Bl -tag -width Ds
.It Cm #
A `#' character
-specifying that the value should be printed in an ``alternative form''.
+specifying that the value should be printed in an ``alternate form''.
For
-.Cm c ,
-.Cm d ,
+.Cm b , c , d , s
and
-.Cm s ,
-formats, this option has no effect. For the
+.Cm u
+formats, this option has no effect.
+For the
.Cm o
formats the precision of the number is increased to force the first
-character of the output string to a zero. For the
+character of the output string to a zero.
+For the
.Cm x
.Pq Cm X
format, a non-zero result has the string
.Li 0x
.Pq Li 0X
-prepended to it. For
-.Cm e ,
-.Cm E ,
-.Cm f ,
-.Cm g ,
+prepended to it.
+For
+.Cm a , A , e , E , f , F , g
and
-.Cm G ,
+.Cm G
formats, the result will always contain a decimal point, even if no
digits follow the point (normally, a decimal point only appears in the
-results of those formats if a digit follows the decimal point). For
+results of those formats if a digit follows the decimal point).
+For
.Cm g
and
.Cm G
a sign placed before the number when using signed formats.
.It Sq \&\ \&
A space specifying that a blank should be left before a positive number
-for a signed format. A `+' overrides a space if both are used;
+for a signed format.
+A `+' overrides a space if both are used;
.It Cm \&0
A zero `0' character indicating that zero-padding should be used
-rather than blank-padding. A `\-' overrides a `0' if both are used;
+rather than blank-padding.
+A `\-' overrides a `0' if both are used;
.El
.It "Field Width:"
An optional digit string specifying a
.Em field width ;
-if the output string has fewer characters than the field width it will
+if the output string has fewer bytes than the field width it will
be blank-padded on the left (or right, if the left-adjustment indicator
has been given) to make up the field width (note that a leading zero
is a flag, but an embedded zero is part of a field width);
which specifies the number of digits to appear after the decimal point,
for
.Cm e
-and
+and
.Cm f
-formats, or the maximum number of characters to be printed
+formats, or the maximum number of bytes to be printed
from a string; if the digit string is missing, the precision is treated
as zero;
.It Format:
A character which indicates the type of format to use (one of
-.Cm diouxXfwEgGbcs ) .
+.Cm diouxXfFeEgGaAcsb ) .
+The uppercase formats differ from their lowercase counterparts only in
+that the output of the former is entirely in uppercase.
+The floating-point format specifiers
+.Pq Cm fFeEgGaA
+may be prefixed by an
+.Cm L
+to request that additional precision be used, if available.
.El
.Pp
A field width or precision may be
.Ar argument
is printed as a signed decimal (d or i), unsigned octal, unsigned decimal,
or unsigned hexadecimal (X or x), respectively.
-.It Cm f
+.It Cm fF
The
.Ar argument
-is printed in the style
-.Sm off
-.Pf [\-]ddd Cm \&. No ddd
-.Sm on
-where the number of d's
+is printed in the style `[\-]ddd.ddd' where the number of d's
after the decimal point is equal to the precision specification for
the argument.
If the precision is missing, 6 digits are given; if the precision
is explicitly 0, no digits and no decimal point are printed.
+The values \*[If] and \*[Na] are printed as
+.Ql inf
+and
+.Ql nan ,
+respectively.
.It Cm eE
The
.Ar argument
-is printed in the style
+is printed in the style
+.Cm e
.Sm off
-.Pf [\-]d Cm \&. No ddd Cm e No \\*(Pmdd
+.Sq Op - Ar d.ddd No \(+- Ar dd
.Sm on
where there
is one digit before the decimal point and the number after is equal to
the precision specification for the argument; when the precision is
missing, 6 digits are produced.
-An upper-case E is used for an `E' format.
+The values \*[If] and \*[Na] are printed as
+.Ql inf
+and
+.Ql nan ,
+respectively.
.It Cm gG
The
.Ar argument
is printed in style
.Cm f
+.Pq Cm F
or in style
.Cm e
.Pq Cm E
whichever gives full precision in minimum space.
-.It Cm b
-Characters from the string
+.It Cm aA
+The
.Ar argument
-are printed with backslash-escape sequences expanded.
+is printed in style
+.Sm off
+.Sq Op - Ar h.hhh No \(+- Li p Ar d
+.Sm on
+where there is one digit before the hexadecimal point and the number
+after is equal to the precision specification for the argument;
+when the precision is missing, enough digits are produced to convey
+the argument's exact double-precision floating-point representation.
+The values \*[If] and \*[Na] are printed as
+.Ql inf
+and
+.Ql nan ,
+respectively.
.It Cm c
-The first character of
+The first byte of
.Ar argument
is printed.
.It Cm s
-Characters from the string
+Bytes from the string
.Ar argument
-are printed until the end is reached or until the number of characters
+are printed until the end is reached or until the number of bytes
indicated by the precision specification is reached; however if the
-precision is 0 or missing, all characters in the string are printed.
+precision is 0 or missing, the string is printed entirely.
+.It Cm b
+As for
+.Cm s ,
+but interpret character escapes in backslash notation in the string
+.Ar argument .
+The permitted escape sequences are slightly different in that
+octal escapes are
+.Cm \e0 Ns Ar num
+instead of
+.Cm \e Ns Ar num .
+.It Cm n$
+Allows reordering of the output according to
+.Ar argument .
.It Cm \&%
Print a `%'; no argument is used.
.El
.Pp
+The decimal point
+character is defined in the program's locale (category
+.Dv LC_NUMERIC ) .
+.Pp
In no case does a non-existent or small field width cause truncation of
a field; padding takes place only if the specified field width exceeds
the actual width.
-.Sh RETURN VALUES
+.Pp
+Some shells may provide a builtin
.Nm
-exits 0 on success, 1 on failure.
+command which is similar or identical to this utility.
+Consult the
+.Xr builtin 1
+manual page.
+.Sh EXIT STATUS
+.Ex -std
+.Sh COMPATIBILITY
+The traditional
+.Bx
+behavior of converting arguments of numeric formats not beginning
+with a digit to the
+.Tn ASCII
+code of the first character is not supported.
.Sh SEE ALSO
+.Xr builtin 1 ,
.Xr echo 1 ,
+.Xr sh 1 ,
.Xr printf 3
.Sh STANDARDS
The
.Nm
-utility conforms to
-.St -p1003.2-92 .
+command is expected to be compatible with the
+.St -p1003.2
+specification.
+.Sh HISTORY
+The
+.Nm
+command appeared in
+.Bx 4.3 Reno .
+It is modeled
+after the standard library function,
+.Xr printf 3 .
+.Sh CAVEATS
+.Tn ANSI
+hexadecimal character constants were deliberately not provided.
+.Pp
+Trying to print a dash ("-") as the first character causes
+.Nm
+to interpret the dash as a program argument.
+.Nm --
+must be used before
+.Ar format .
+.Pp
+If the locale contains multibyte characters
+(such as UTF-8),
+the
+.Cm c
+format and
+.Cm b
+and
+.Cm s
+formats with a precision
+may not operate as expected.
.Sh BUGS
Since the floating point numbers are translated from
.Tn ASCII
to floating-point and
then back again, floating-point precision may be lost.
+(By default, the number is translated to an IEEE-754 double-precision
+value before being printed.
+The
+.Cm L
+modifier may produce additional precision, depending on the hardware platform.)
+.Pp
+The escape sequence \e000 is the string terminator.
+When present in the argument for the
+.Cm b
+format, the argument will be truncated at the \e000 character.
+.Pp
+Multibyte characters are not recognized in format strings (this is only
+a problem if
+.Ql %
+can appear inside a multibyte character).
projects / apple / shell_cmds.git / blobdiff