1.\" $NetBSD: printf.1,v 1.15 2002/02/08 01:36:31 ross Exp $ 2.\" 3.\" Copyright (c) 1989, 1990, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" This code is derived from software contributed to Berkeley by 7.\" the Institute of Electrical and Electronics Engineers, Inc. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 3. All advertising materials mentioning features or use of this software 18.\" must display the following acknowledgement: 19.\" This product includes software developed by the University of 20.\" California, Berkeley and its contributors. 21.\" 4. Neither the name of the University nor the names of its contributors 22.\" may be used to endorse or promote products derived from this software 23.\" without specific prior written permission. 24.\" 25.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 26.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 27.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 28.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 29.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 30.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 31.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 32.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 34.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35.\" SUCH DAMAGE. 36.\" 37.\" from: @(#)printf.1 8.1 (Berkeley) 6/6/93 38.\" 39.Dd November 5, 1993 40.Dt PRINTF 1 41.Os 42.Sh NAME 43.Nm printf 44.Nd formatted output 45.Sh SYNOPSIS 46.Nm 47.Ar format 48.Op Ar arguments ... 49.Sh DESCRIPTION 50.Nm 51formats and prints its arguments, after the first, under control 52of the 53.Ar format . 54The 55.Ar format 56is a character string which contains three types of objects: plain characters, 57which are simply copied to standard output, character escape sequences which 58are converted and copied to the standard output, and format specifications, 59each of which causes printing of the next successive 60.Ar argument . 61.Pp 62The 63.Ar arguments 64after the first are treated as strings if the corresponding format is 65either 66.Cm b , 67.Cm c 68or 69.Cm s ; 70otherwise it is evaluated as a C constant, with the following extensions: 71.Pp 72.Bl -bullet -offset indent -compact 73.It 74A leading plus or minus sign is allowed. 75.It 76If the leading character is a single or double quote, the value is the 77.Tn ASCII 78code of the next character. 79.El 80.Pp 81The format string is reused as often as necessary to satisfy the 82.Ar arguments . 83Any extra format specifications are evaluated with zero or the null 84string. 85.Pp 86Character escape sequences are in backslash notation as defined in 87.St -ansiC . 88The characters and their meanings 89are as follows: 90.Bl -tag -width Ds -offset indent 91.It Cm \ee 92Write an \*[Lt]escape\*[Gt] character. 93.It Cm \ea 94Write a \*[Lt]bell\*[Gt] character. 95.It Cm \eb 96Write a \*[Lt]backspace\*[Gt] character. 97.It Cm \ef 98Write a \*[Lt]form-feed\*[Gt] character. 99.It Cm \en 100Write a \*[Lt]new-line\*[Gt] character. 101.It Cm \er 102Write a \*[Lt]carriage return\*[Gt] character. 103.It Cm \et 104Write a \*[Lt]tab\*[Gt] character. 105.It Cm \ev 106Write a \*[Lt]vertical tab\*[Gt] character. 107.It Cm \e\' 108Write a \*[Lt]single quote\*[Gt] character. 109.It Cm \e\e 110Write a backslash character. 111.It Cm \e Ns Ar num 112Write an 8-bit character whose 113.Tn ASCII 114value is the 1-, 2-, or 3-digit 115octal number 116.Ar num . 117.El 118.Pp 119Each format specification is introduced by the percent character 120(``%''). 121The remainder of the format specification includes, 122in the following order: 123.Bl -tag -width Ds 124.It "Zero or more of the following flags:" 125.Bl -tag -width Ds 126.It Cm # 127A `#' character 128specifying that the value should be printed in an ``alternative form''. 129For 130.Cm c , 131.Cm d , 132and 133.Cm s , 134formats, this option has no effect. For the 135.Cm o 136formats the precision of the number is increased to force the first 137character of the output string to a zero. For the 138.Cm x 139.Pq Cm X 140format, a non-zero result has the string 141.Li 0x 142.Pq Li 0X 143prepended to it. For 144.Cm e , 145.Cm E , 146.Cm f , 147.Cm g , 148and 149.Cm G , 150formats, the result will always contain a decimal point, even if no 151digits follow the point (normally, a decimal point only appears in the 152results of those formats if a digit follows the decimal point). For 153.Cm g 154and 155.Cm G 156formats, trailing zeros are not removed from the result as they 157would otherwise be; 158.It Cm \&\- 159A minus sign `\-' which specifies 160.Em left adjustment 161of the output in the indicated field; 162.It Cm \&+ 163A `+' character specifying that there should always be 164a sign placed before the number when using signed formats. 165.It Sq \&\ \& 166A space specifying that a blank should be left before a positive number 167for a signed format. A `+' overrides a space if both are used; 168.It Cm \&0 169A zero `0' character indicating that zero-padding should be used 170rather than blank-padding. A `\-' overrides a `0' if both are used; 171.El 172.It "Field Width:" 173An optional digit string specifying a 174.Em field width ; 175if the output string has fewer characters than the field width it will 176be blank-padded on the left (or right, if the left-adjustment indicator 177has been given) to make up the field width (note that a leading zero 178is a flag, but an embedded zero is part of a field width); 179.It Precision : 180An optional period, 181.Sq Cm \&.\& , 182followed by an optional digit string giving a 183.Em precision 184which specifies the number of digits to appear after the decimal point, 185for 186.Cm e 187and 188.Cm f 189formats, or the maximum number of characters to be printed 190from a string; if the digit string is missing, the precision is treated 191as zero; 192.It Format : 193A character which indicates the type of format to use (one of 194.Cm diouxXfwEgGbcs ) . 195.El 196.Pp 197A field width or precision may be 198.Sq Cm \&* 199instead of a digit string. 200In this case an 201.Ar argument 202supplies the field width or precision. 203.Pp 204The format characters and their meanings are: 205.Bl -tag -width Fl 206.It Cm diouXx 207The 208.Ar argument 209is printed as a signed decimal (d or i), unsigned octal, unsigned decimal, 210or unsigned hexadecimal (X or x), respectively. 211.It Cm f 212The 213.Ar argument 214is printed in the style 215.Sm off 216.Pf [\-]ddd Cm \&. No ddd 217.Sm on 218where the number of d's 219after the decimal point is equal to the precision specification for 220the argument. 221If the precision is missing, 6 digits are given; if the precision 222is explicitly 0, no digits and no decimal point are printed. 223.It Cm eE 224The 225.Ar argument 226is printed in the style 227.Sm off 228.Pf [\-]d Cm \&. No ddd Cm e No \\*(Pmdd 229.Sm on 230where there 231is one digit before the decimal point and the number after is equal to 232the precision specification for the argument; when the precision is 233missing, 6 digits are produced. 234An upper-case E is used for an `E' format. 235.It Cm gG 236The 237.Ar argument 238is printed in style 239.Cm f 240or in style 241.Cm e 242.Pq Cm E 243whichever gives full precision in minimum space. 244.It Cm b 245Characters from the string 246.Ar argument 247are printed with backslash-escape sequences expanded. 248.It Cm c 249The first character of 250.Ar argument 251is printed. 252.It Cm s 253Characters from the string 254.Ar argument 255are printed until the end is reached or until the number of characters 256indicated by the precision specification is reached; however if the 257precision is 0 or missing, all characters in the string are printed. 258.It Cm \&% 259Print a `%'; no argument is used. 260.El 261.Pp 262In no case does a non-existent or small field width cause truncation of 263a field; padding takes place only if the specified field width exceeds 264the actual width. 265.Sh EXIT STATUS 266.Nm 267exits 0 on success, 1 on failure. 268.Sh SEE ALSO 269.Xr echo 1 , 270.Xr printf 3 , 271.Xr printf 9 272.Sh STANDARDS 273The 274.Nm 275utility conforms to 276.St -p1003.2-92 . 277.Sh BUGS 278Since the floating point numbers are translated from 279.Tn ASCII 280to floating-point and 281then back again, floating-point precision may be lost. 282