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. Neither the name of the University nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.\" @(#)printf.1 8.1 (Berkeley) 6/6/93 32.\" $FreeBSD: src/usr.bin/printf/printf.1,v 1.37 2010/11/19 12:56:13 jilles Exp $ 33.\" 34.Dd November 19, 2010 35.Dt PRINTF 1 36.Os 37.Sh NAME 38.Nm printf 39.Nd formatted output 40.Sh SYNOPSIS 41.Nm 42.Ar format Op Ar arguments ... 43.Sh DESCRIPTION 44The 45.Nm 46utility formats and prints its arguments, after the first, under control 47of the 48.Ar format . 49The 50.Ar format 51is a character string which contains three types of objects: plain characters, 52which are simply copied to standard output, character escape sequences which 53are converted and copied to the standard output, and format specifications, 54each of which causes printing of the next successive 55.Ar argument . 56.Pp 57The 58.Ar arguments 59after the first are treated as strings if the corresponding format is 60either 61.Cm c , b 62or 63.Cm s ; 64otherwise it is evaluated as a C constant, with the following extensions: 65.Pp 66.Bl -bullet -offset indent -compact 67.It 68A leading plus or minus sign is allowed. 69.It 70If the leading character is a single or double quote, the value is the 71.Tn ASCII 72code of the next character. 73.El 74.Pp 75The format string is reused as often as necessary to satisfy the 76.Ar arguments . 77Any extra format specifications are evaluated with zero or the null 78string. 79.Pp 80Character escape sequences are in backslash notation as defined in the 81.St -ansiC , 82with extensions. 83The characters and their meanings 84are as follows: 85.Pp 86.Bl -tag -width Ds -offset indent -compact 87.It Cm \ea 88Write a <bell> character. 89.It Cm \eb 90Write a <backspace> character. 91.It Cm \ec 92Ignore remaining characters in this string. 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 a byte whose 109value is the 1-, 2-, or 3-digit 110octal number 111.Ar num . 112Multibyte characters can be constructed using multiple 113.Cm \e Ns Ar num 114sequences. 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 ``alternate form''. 127For 128.Cm c , d , 129and 130.Cm s , 131formats, this option has no effect. 132For the 133.Cm o 134formats the precision of the number is increased to force the first 135character of the output string to a zero. 136For the 137.Cm x 138.Pq Cm X 139format, a non-zero result has the string 140.Li 0x 141.Pq Li 0X 142prepended to it. 143For 144.Cm e , E , f , g , 145and 146.Cm G , 147formats, the result will always contain a decimal point, even if no 148digits follow the point (normally, a decimal point only appears in the 149results of those formats if a digit follows the decimal point). 150For 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. 166A `+' overrides a space if both are used; 167.It Cm \&0 168A zero `0' character indicating that zero-padding should be used 169rather than blank-padding. 170A `\-' 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 diouxXfFeEgGaAcsb ) . 195The uppercase formats differ from their lowercase counterparts only in 196that the output of the former is entirely in uppercase. 197The floating-point format specifiers 198.Pq Cm fFeEgGaA 199may be prefixed by an 200.Cm L 201to request that additional precision be used, if available. 202.El 203.Pp 204A field width or precision may be 205.Sq Cm \&* 206instead of a digit string. 207In this case an 208.Ar argument 209supplies the field width or precision. 210.Pp 211The format characters and their meanings are: 212.Bl -tag -width Fl 213.It Cm diouXx 214The 215.Ar argument 216is printed as a signed decimal (d or i), unsigned octal, unsigned decimal, 217or unsigned hexadecimal (X or x), respectively. 218.It Cm fF 219The 220.Ar argument 221is printed in the style `[\-]ddd.ddd' where the number of d's 222after the decimal point is equal to the precision specification for 223the argument. 224If the precision is missing, 6 digits are given; if the precision 225is explicitly 0, no digits and no decimal point are printed. 226The values \*[If] and \*[Na] are printed as 227.Ql inf 228and 229.Ql nan , 230respectively. 231.It Cm eE 232The 233.Ar argument 234is printed in the style 235.Cm e 236.Sm off 237.Sq Op - Ar d.ddd No \(+- Ar dd 238.Sm on 239where there 240is one digit before the decimal point and the number after is equal to 241the precision specification for the argument; when the precision is 242missing, 6 digits are produced. 243The values \*[If] and \*[Na] are printed as 244.Ql inf 245and 246.Ql nan , 247respectively. 248.It Cm gG 249The 250.Ar argument 251is printed in style 252.Cm f 253.Pq Cm F 254or in style 255.Cm e 256.Pq Cm E 257whichever gives full precision in minimum space. 258.It Cm aA 259The 260.Ar argument 261is printed in style 262.Sm off 263.Sq Op - Ar h.hhh No \(+- Li p Ar d 264.Sm on 265where there is one digit before the hexadecimal point and the number 266after is equal to the precision specification for the argument; 267when the precision is missing, enough digits are produced to convey 268the argument's exact double-precision floating-point representation. 269The values \*[If] and \*[Na] are printed as 270.Ql inf 271and 272.Ql nan , 273respectively. 274.It Cm c 275The first character of 276.Ar argument 277is printed. 278.It Cm s 279Characters from the string 280.Ar argument 281are printed until the end is reached or until the number of characters 282indicated by the precision specification is reached; however if the 283precision is 0 or missing, all characters in the string are printed. 284.It Cm b 285As for 286.Cm s , 287but interpret character escapes in backslash notation in the string 288.Ar argument . 289The permitted escape sequences are slightly different in that 290octal escapes are 291.Cm \e0 Ns Ar num 292instead of 293.Cm \e Ns Ar num . 294.It Cm \&% 295Print a `%'; no argument is used. 296.El 297.Pp 298The decimal point 299character is defined in the program's locale (category 300.Dv LC_NUMERIC ) . 301.Pp 302In no case does a non-existent or small field width cause truncation of 303a field; padding takes place only if the specified field width exceeds 304the actual width. 305.Pp 306Some shells may provide a builtin 307.Nm 308command which is similar or identical to this utility. 309Consult the 310.Xr builtin 1 311manual page. 312.Sh EXIT STATUS 313.Ex -std 314.Sh COMPATIBILITY 315The traditional 316.Bx 317behavior of converting arguments of numeric formats not beginning 318with a digit to the 319.Tn ASCII 320code of the first character is not supported. 321.Sh SEE ALSO 322.Xr builtin 1 , 323.Xr echo 1 , 324.Xr sh 1 , 325.Xr printf 3 326.Sh STANDARDS 327The 328.Nm 329command is expected to be compatible with the 330.St -p1003.2 331specification. 332.Sh HISTORY 333The 334.Nm 335command appeared in 336.Bx 4.3 Reno . 337It is modeled 338after the standard library function, 339.Xr printf 3 . 340.Sh BUGS 341Since the floating point numbers are translated from 342.Tn ASCII 343to floating-point and 344then back again, floating-point precision may be lost. 345(By default, the number is translated to an IEEE-754 double-precision 346value before being printed. 347The 348.Cm L 349modifier may produce additional precision, depending on the hardware platform.) 350.Pp 351.Tn ANSI 352hexadecimal character constants were deliberately not provided. 353.Pp 354The escape sequence \e000 is the string terminator. 355When present in the argument for the 356.Cm b 357format, the argument will be truncated at the \e000 character. 358.Pp 359Multibyte characters are not recognized in format strings (this is only 360a problem if 361.Ql % 362can appear inside a multibyte character). 363