1.\" Copyright (c) 1989, 1990, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" the Institute of Electrical and Electronics Engineers, Inc. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. All advertising materials mentioning features or use of this software 16.\" must display the following acknowledgement: 17.\" This product includes software developed by the University of 18.\" California, Berkeley and its contributors. 19.\" 4. Neither the name of the University nor the names of its contributors 20.\" may be used to endorse or promote products derived from this software 21.\" without specific prior written permission. 22.\" 23.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33.\" SUCH DAMAGE. 34.\" 35.\" @(#)printf.1 8.1 (Berkeley) 6/6/93 36.\" $FreeBSD$ 37.\" 38.Dd June 6, 1993 39.Dt PRINTF 1 40.Os 41.Sh NAME 42.Nm printf 43.Nd formatted output 44.Sh SYNOPSIS 45.Nm 46.Ar format Op Ar arguments ... 47.Sh DESCRIPTION 48The 49.Nm 50utility formats and prints its arguments, after the first, under control 51of the 52.Ar format . 53The 54.Ar format 55is a character string which contains three types of objects: plain characters, 56which are simply copied to standard output, character escape sequences which 57are converted and copied to the standard output, and format specifications, 58each of which causes printing of the next successive 59.Ar argument . 60.Pp 61The 62.Ar arguments 63after the first are treated as strings if the corresponding format is 64either 65.Cm c 66or 67.Cm s ; 68otherwise it is evaluated as a C constant, with the following extensions: 69.Pp 70.Bl -bullet -offset indent -compact 71.It 72A leading plus or minus sign is allowed. 73.It 74If the leading character is a single or double quote, or not a digit, 75plus, or minus sign, the value is the ASCII code of the next character. 76.El 77.Pp 78The format string is reused as often as necessary to satisfy the 79.Ar arguments . 80Any extra format specifications are evaluated with zero or the null 81string. 82.Pp 83Character escape sequences are in backslash notation as defined in the 84.St -ansiC . 85The characters and their meanings 86are as follows: 87.Pp 88.Bl -tag -width Ds -offset indent -compact 89.It Cm \ea 90Write a <bell> character. 91.It Cm \eb 92Write a <backspace> character. 93.It Cm \ef 94Write a <form-feed> character. 95.It Cm \en 96Write a <new-line> character. 97.It Cm \er 98Write a <carriage return> character. 99.It Cm \et 100Write a <tab> character. 101.It Cm \ev 102Write a <vertical tab> character. 103.It Cm \e\' 104Write a <single quote> character. 105.It Cm \e\e 106Write a backslash character. 107.It Cm \e Ns Ar num 108Write an 8-bit character whose 109.Tn ASCII 110value is the 1-, 2-, or 3-digit 111octal number 112.Ar num . 113.El 114.Pp 115Each format specification is introduced by the percent character 116(``%''). 117The remainder of the format specification includes, 118in the following order: 119.Bl -tag -width Ds 120.It "Zero or more of the following flags:" 121.Bl -tag -width Ds 122.It Cm # 123A `#' character 124specifying that the value should be printed in an ``alternate form''. 125For 126.Cm c , 127.Cm d , 128and 129.Cm s , 130formats, this option has no effect. For the 131.Cm o 132formats the precision of the number is increased to force the first 133character of the output string to a zero. For the 134.Cm x 135.Pq Cm X 136format, a non-zero result has the string 137.Li 0x 138.Pq Li 0X 139prepended to it. For 140.Cm e , 141.Cm E , 142.Cm f , 143.Cm g , 144and 145.Cm G , 146formats, the result will always contain a decimal point, even if no 147digits follow the point (normally, a decimal point only appears in the 148results of those formats if a digit follows the decimal point). For 149.Cm g 150and 151.Cm G 152formats, trailing zeros are not removed from the result as they 153would otherwise be; 154.It Cm \&\- 155A minus sign `\-' which specifies 156.Em left adjustment 157of the output in the indicated field; 158.It Cm \&+ 159A `+' character specifying that there should always be 160a sign placed before the number when using signed formats. 161.It Sq \&\ \& 162A space specifying that a blank should be left before a positive number 163for a signed format. A `+' overrides a space if both are used; 164.It Cm \&0 165A zero `0' character indicating that zero-padding should be used 166rather than blank-padding. A `\-' overrides a `0' if both are used; 167.El 168.It "Field Width:" 169An optional digit string specifying a 170.Em field width ; 171if the output string has fewer characters than the field width it will 172be blank-padded on the left (or right, if the left-adjustment indicator 173has been given) to make up the field width (note that a leading zero 174is a flag, but an embedded zero is part of a field width); 175.It Precision: 176An optional period, 177.Sq Cm \&.\& , 178followed by an optional digit string giving a 179.Em precision 180which specifies the number of digits to appear after the decimal point, 181for 182.Cm e 183and 184.Cm f 185formats, or the maximum number of characters to be printed 186from a string; if the digit string is missing, the precision is treated 187as zero; 188.It Format: 189A character which indicates the type of format to use (one of 190.Cm diouxXfwEgGcs ) . 191.El 192.Pp 193A field width or precision may be 194.Sq Cm \&* 195instead of a digit string. 196In this case an 197.Ar argument 198supplies the field width or precision. 199.Pp 200The format characters and their meanings are: 201.Bl -tag -width Fl 202.It Cm diouXx 203The 204.Ar argument 205is printed as a signed decimal (d or i), unsigned octal, unsigned decimal, 206or unsigned hexadecimal (X or x), respectively. 207.It Cm f 208The 209.Ar argument 210is printed in the style `[\-]ddd.ddd' where the number of d's 211after the decimal point is equal to the precision specification for 212the argument. 213If the precision is missing, 6 digits are given; if the precision 214is explicitly 0, no digits and no decimal point are printed. 215.It Cm eE 216The 217.Ar argument 218is printed in the style 219.Cm e 220.Sm off 221.Sq Op - Ar d.ddd No \(+- Ar dd 222.Sm on 223where there 224is one digit before the decimal point and the number after is equal to 225the precision specification for the argument; when the precision is 226missing, 6 digits are produced. 227An upper-case E is used for an `E' format. 228.It Cm gG 229The 230.Ar argument 231is printed in style 232.Cm f 233or in style 234.Cm e 235.Pq Cm E 236whichever gives full precision in minimum space. 237.It Cm c 238The first character of 239.Ar argument 240is printed. 241.It Cm s 242Characters from the string 243.Ar argument 244are printed until the end is reached or until the number of characters 245indicated by the precision specification is reached; however if the 246precision is 0 or missing, all characters in the string are printed. 247.It Cm \&% 248Print a `%'; no argument is used. 249.El 250.Pp 251The decimal point 252character is defined in the program's locale (category 253.Dv LC_NUMERIC ) . 254.Pp 255In no case does a non-existent or small field width cause truncation of 256a field; padding takes place only if the specified field width exceeds 257the actual width. 258.Sh DIAGNOSTICS 259.Ex -std 260.Sh SEE ALSO 261.Xr printf 3 262.Sh HISTORY 263The 264.Nm 265command appeared in 266.Bx 4.3 Reno . 267It is modeled 268after the standard library function, 269.Xr printf 3 . 270.Sh BUGS 271Since the floating point numbers are translated from 272.Tn ASCII 273to floating-point and 274then back again, floating-point precision may be lost. 275.Pp 276.Tn ANSI 277hexadecimal character constants were deliberately not provided. 278.Pp 279The escape sequence \e000 is the string terminator. When present in the 280.Ar format , 281the 282.Ar format 283will be truncated at the \e000 character. 284