1.\" $NetBSD: printf.1,v 1.9 1997/11/08 09:34:24 lukem 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 \ea 92Write a <bell> character. 93.It Cm \eb 94Write a <backspace> character. 95.It Cm \ef 96Write a <form-feed> character. 97.It Cm \en 98Write a <new-line> character. 99.It Cm \er 100Write a <carriage return> character. 101.It Cm \et 102Write a <tab> character. 103.It Cm \ev 104Write a <vertical tab> character. 105.It Cm \e\' 106Write a <single quote> character. 107.It Cm \e\e 108Write a backslash character. 109.It Cm \e Ns Ar num 110Write an 8-bit character whose 111.Tn ASCII 112value is the 1-, 2-, or 3-digit 113octal number 114.Ar num . 115.El 116.Pp 117Each format specification is introduced by the percent character 118(``%''). 119The remainder of the format specification includes, 120in the following order: 121.Bl -tag -width Ds 122.It "Zero or more of the following flags:" 123.Bl -tag -width Ds 124.It Cm # 125A `#' character 126specifying that the value should be printed in an ``alternative form''. 127For 128.Cm c , 129.Cm d , 130and 131.Cm s , 132formats, this option has no effect. For the 133.Cm o 134formats the precision of the number is increased to force the first 135character of the output string to a zero. For the 136.Cm x 137.Pq Cm X 138format, a non-zero result has the string 139.Li 0x 140.Pq Li 0X 141prepended to it. For 142.Cm e , 143.Cm E , 144.Cm f , 145.Cm g , 146and 147.Cm G , 148formats, the result will always contain a decimal point, even if no 149digits follow the point (normally, a decimal point only appears in the 150results of those formats if a digit follows the decimal point). For 151.Cm g 152and 153.Cm G 154formats, trailing zeros are not removed from the result as they 155would otherwise be; 156.It Cm \&\- 157A minus sign `\-' which specifies 158.Em left adjustment 159of the output in the indicated field; 160.It Cm \&+ 161A `+' character specifying that there should always be 162a sign placed before the number when using signed formats. 163.It Sq \&\ \& 164A space specifying that a blank should be left before a positive number 165for a signed format. A `+' overrides a space if both are used; 166.It Cm \&0 167A zero `0' character indicating that zero-padding should be used 168rather than blank-padding. A `\-' overrides a `0' if both are used; 169.El 170.It "Field Width:" 171An optional digit string specifying a 172.Em field width ; 173if the output string has fewer characters than the field width it will 174be blank-padded on the left (or right, if the left-adjustment indicator 175has been given) to make up the field width (note that a leading zero 176is a flag, but an embedded zero is part of a field width); 177.It Precision: 178An optional period, 179.Sq Cm \&.\& , 180followed by an optional digit string giving a 181.Em precision 182which specifies the number of digits to appear after the decimal point, 183for 184.Cm e 185and 186.Cm f 187formats, or the maximum number of characters to be printed 188from a string; if the digit string is missing, the precision is treated 189as zero; 190.It Format: 191A character which indicates the type of format to use (one of 192.Cm diouxXfwEgGbcs ) . 193.El 194.Pp 195A field width or precision may be 196.Sq Cm \&* 197instead of a digit string. 198In this case an 199.Ar argument 200supplies the field width or precision. 201.Pp 202The format characters and their meanings are: 203.Bl -tag -width Fl 204.It Cm diouXx 205The 206.Ar argument 207is printed as a signed decimal (d or i), unsigned octal, unsigned decimal, 208or unsigned hexadecimal (X or x), respectively. 209.It Cm f 210The 211.Ar argument 212is printed in the style 213.Sm off 214.Pf [\-]ddd Cm \&. No ddd 215.Sm on 216where the number of d's 217after the decimal point is equal to the precision specification for 218the argument. 219If the precision is missing, 6 digits are given; if the precision 220is explicitly 0, no digits and no decimal point are printed. 221.It Cm eE 222The 223.Ar argument 224is printed in the style 225.Sm off 226.Pf [\-]d Cm \&. No ddd Cm e No \\*(Pmdd 227.Sm on 228where there 229is one digit before the decimal point and the number after is equal to 230the precision specification for the argument; when the precision is 231missing, 6 digits are produced. 232An upper-case E is used for an `E' format. 233.It Cm gG 234The 235.Ar argument 236is printed in style 237.Cm f 238or in style 239.Cm e 240.Pq Cm E 241whichever gives full precision in minimum space. 242.It Cm b 243Characters from the string 244.Ar argument 245are printed with backslash-escape sequences expanded. 246.It Cm c 247The first character of 248.Ar argument 249is printed. 250.It Cm s 251Characters from the string 252.Ar argument 253are printed until the end is reached or until the number of characters 254indicated by the precision specification is reached; however if the 255precision is 0 or missing, all characters in the string are printed. 256.It Cm \&% 257Print a `%'; no argument is used. 258.El 259.Pp 260In no case does a non-existent or small field width cause truncation of 261a field; padding takes place only if the specified field width exceeds 262the actual width. 263.Sh RETURN VALUES 264.Nm 265exits 0 on success, 1 on failure. 266.Sh SEE ALSO 267.Xr echo 1 , 268.Xr printf 3 269.Sh STANDARDS 270The 271.Nm 272utility conforms to 273.St -p1003.2-92 . 274.Sh BUGS 275Since the floating point numbers are translated from 276.Tn ASCII 277to floating-point and 278then back again, floating-point precision may be lost. 279