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PRINTF(1)		  BSD General Commands Manual		     PRINTF(1)

     printf -- formatted output

     printf format [arguments ...]

     printf formats and	prints its arguments, after the	first, under control
     of	the format.  The 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 argument.

     The arguments after the first are treated as strings if the corresponding
     format is either b, B, c, or s; otherwise it is evaluated as a C con-
     stant, with the following extensions:

	   +o   A leading plus or minus sign is allowed.
	   +o   If the leading character	is a single or double quote, the value
	       is the ASCII code of the	next character.

     The format	string is reused as often as necessary to satisfy the
     arguments.	 Any extra format specifications are evaluated with zero or
     the null string.

     Character escape sequences	are in backslash notation as defined in	ANSI
     X3.159-1989 ("ANSI	C89").	The characters and their meanings are as fol-

	   \e	   Write an <escape> character.

	   \a	   Write a <bell> character.

	   \b	   Write a <backspace> character.

	   \f	   Write a <form-feed> character.

	   \n	   Write a <new-line> character.

	   \r	   Write a <carriage return> character.

	   \t	   Write a <tab> character.

	   \v	   Write a <vertical tab> character.

	   \'	   Write a <single quote> character.

	   \"	   Write a <double quote> character.

	   \\	   Write a backslash character.

	   \num	   Write an 8-bit character whose ASCII	value is the 1-, 2-,
		   or 3-digit octal number num.

	   \xxx	   Write an 8-bit character whose ASCII	value is the 1-	or
		   2-digit hexadecimal number xx.

     Each format specification is introduced by	the percent character ("%").
     The remainder of the format specification includes, in the	following or-

     Zero or more of the following flags:

	     #	     A `#' character specifying	that the value should be
		     printed in	an "alternative	form".	For b, c, d, and s
		     formats, this option has no effect.  For the o format the
		     precision of the number is	increased to force the first
		     character of the output string to a zero.	For the	x (X)
		     format, a non-zero	result has the string 0x (0X)
		     prepended to it.  For e, E, f, g, and G formats, the re-
		     sult will always contain a	decimal	point, even if no dig-
		     its follow	the point (normally, a decimal point only ap-
		     pears in the results of those formats if a	digit follows
		     the decimal point).  For g	and G formats, trailing	zeros
		     are not removed from the result as	they would otherwise

	     -	     A minus sign `-' which specifies left adjustment of the
		     output in the indicated field;

	     +	     A `+' character specifying	that there should always be a
		     sign placed before	the number when	using signed formats.

	     ` '     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;

	     0	     A zero `0'	character indicating that zero-padding should
		     be	used rather than blank-padding.	 A `-' overrides a `0'
		     if	both are used;

     Field Width:
	     An	optional digit string specifying a field width;	if the output
	     string has	fewer characters than the field	width it will be
	     blank-padded on the left (or right, if the	left-adjustment	indi-
	     cator 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

	     An	optional period, `.', followed by an optional digit string
	     giving a precision	which specifies	the number of digits to	appear
	     after the decimal point, for e and	f formats, or the maximum num-
	     ber of characters to be printed from a string (b, B, and s	for-
	     mats); if the digit string	is missing, the	precision is treated
	     as	zero;

	     A character which indicates the type of format to use (one	of

     A field width or precision	may be `*' instead of a	digit string.  In this
     case an argument supplies the field width or precision.

     The format	characters and their meanings are:

     diouXx	 The argument is printed as a signed decimal (d	or i), un-
		 signed	octal, unsigned	decimal, or unsigned hexadecimal (X or
		 x), respectively.

     f		 The argument is printed in the	style [-]ddd.ddd where the
		 number	of d's after the decimal point is equal	to the preci-
		 sion 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.

     eE		 The argument is printed in the	style [-]d.ddde+-dd where
		 there is one digit before the decimal point and the number
		 after is equal	to the precision specification for the argu-
		 ment; when the	precision is missing, 6	digits are produced.
		 An upper-case E is used for an	`E' format.

     gG		 The argument is printed in style f or in style	e (E) which-
		 ever gives full precision in minimum space.

     b		 Characters from the string argument are printed with back-
		 slash-escape sequences	expanded.

		 The following additional backslash-escape sequences are sup-

		 \c	 Causes	printf to ignore any remaining characters in
			 the string operand containing it, any remaining
			 string	operands, and any additional characters	in the
			 format	operand.

		 \0num	 Write an 8-bit	character whose	ASCII value is the 1-,
			 2-, or	3-digit	octal number num.

		 \^c	 Write the control character c.	 Generates characters
			 `\000'	through	`\037`,	and `\177' (from `\^?').

		 \M-c	 Write the character c with the	8th bit	set.  Gener-
			 ates characters `\241'	through	`\376`.

		 \M^c	 Write the control character c with the	8th bit	set.
			 Generates characters `\200' through `\237`, and
			 `\377'	(from `\M^?').

     B		 Characters from the string argument are printed with unprint-
		 able characters backslash-escaped using the
		 `\c',`\^c',`\M-c'or `\M^c', formats described above.

     c		 The first character of	argument is printed.

     s		 Characters from the string argument are printed until the end
		 is reached or until the number	of characters indicated	by the
		 precision specification is reached; if	the precision is omit-
		 ted, all characters in	the string are printed.

     %		 Print a `%'; no argument is used.

     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.

     printf exits 0 on success,	1 on failure.

     echo(1), printf(3), vis(3), printf(9)

     The printf	utility	conforms to IEEE Std 1003.1-2001 ("POSIX.1").

     Support for the floating point formats and	`*' as a field width and pre-
     cision are	optional in POSIX.

     The behaviour of the %B format and	the \',	\", \xxx, \e and \[M][-|^]c
     escape sequences are undefined in POSIX.

     Since the floating	point numbers are translated from ASCII	to floating-
     point and then back again,	floating-point precision may be	lost.

     Hexadecimal character constants are restricted to,	and should be speci-
     fied as, two character constants.	This is	contrary to the	ISO C standard
     but does guarantee	detection of the end of	the constant.

     All formats which treat the argument as a number first convert the
     argument from its external	representation as a character string to	an in-
     ternal numeric representation, and	then apply the format to the internal
     numeric representation, producing another external	character string rep-
     resentation.  One might expect the	%c format to do	likewise, but in fact
     it	does not.

     To	convert	a string representation	of a decimal, octal, or	hexadecimal
     number into the corresponding character, two nested printf	invocations
     may be used, in which the inner invocation	converts the input to an octal
     string, and the outer invocation uses the octal string as part of a for-
     mat.  For example,	the following command outputs the character whose code
     is	0x0A, which is a newline in ASCII:

	   printf "$(printf "\\%o" "0x0A")"

BSD				  May 6, 2008				   BSD


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