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 , 66.Cm b 67or 68.Cm s ; 69otherwise it is evaluated as a C constant, with the following extensions: 70.Pp 71.Bl -bullet -offset indent -compact 72.It 73A leading plus or minus sign is allowed. 74.It 75If the leading character is a single or double quote the value is the ASCII 76code of the next character. 77.El 78.Pp 79The format string is reused as often as necessary to satisfy the 80.Ar arguments . 81Any extra format specifications are evaluated with zero or the null 82string. 83.Pp 84Character escape sequences are in backslash notation as defined in the 85.St -ansiC , 86with extensions. 87The characters and their meanings 88are as follows: 89.Pp 90.Bl -tag -width Ds -offset indent -compact 91.It Cm \ea 92Write a <bell> character. 93.It Cm \eb 94Write a <backspace> character. 95.It Cm \ec 96Ignore remaining characters in this string. 97.It Cm \ef 98Write a <form-feed> character. 99.It Cm \en 100Write a <new-line> character. 101.It Cm \er 102Write a <carriage return> character. 103.It Cm \et 104Write a <tab> character. 105.It Cm \ev 106Write a <vertical tab> character. 107.It Cm \e\' 108Write a <single quote> character. 109.It Cm \e\e 110Write a backslash character. 111.It Cm \e Ns Ar num 112.It Cm \e0 Ns Ar num 113Write an 8-bit character whose 114.Tn ASCII 115value is the 1-, 2-, or 3-digit 116octal number 117.Ar num . 118.El 119.Pp 120Each format specification is introduced by the percent character 121(``%''). 122The remainder of the format specification includes, 123in the following order: 124.Bl -tag -width Ds 125.It "Zero or more of the following flags:" 126.Bl -tag -width Ds 127.It Cm # 128A `#' character 129specifying that the value should be printed in an ``alternate form''. 130For 131.Cm c , 132.Cm d , 133and 134.Cm s , 135formats, this option has no effect. For the 136.Cm o 137formats the precision of the number is increased to force the first 138character of the output string to a zero. For the 139.Cm x 140.Pq Cm X 141format, a non-zero result has the string 142.Li 0x 143.Pq Li 0X 144prepended to it. For 145.Cm e , 146.Cm E , 147.Cm f , 148.Cm g , 149and 150.Cm G , 151formats, the result will always contain a decimal point, even if no 152digits follow the point (normally, a decimal point only appears in the 153results of those formats if a digit follows the decimal point). For 154.Cm g 155and 156.Cm G 157formats, trailing zeros are not removed from the result as they 158would otherwise be; 159.It Cm \&\- 160A minus sign `\-' which specifies 161.Em left adjustment 162of the output in the indicated field; 163.It Cm \&+ 164A `+' character specifying that there should always be 165a sign placed before the number when using signed formats. 166.It Sq \&\ \& 167A space specifying that a blank should be left before a positive number 168for a signed format. A `+' overrides a space if both are used; 169.It Cm \&0 170A zero `0' character indicating that zero-padding should be used 171rather than blank-padding. A `\-' overrides a `0' if both are used; 172.El 173.It "Field Width:" 174An optional digit string specifying a 175.Em field width ; 176if the output string has fewer characters than the field width it will 177be blank-padded on the left (or right, if the left-adjustment indicator 178has been given) to make up the field width (note that a leading zero 179is a flag, but an embedded zero is part of a field width); 180.It Precision: 181An optional period, 182.Sq Cm \&.\& , 183followed by an optional digit string giving a 184.Em precision 185which specifies the number of digits to appear after the decimal point, 186for 187.Cm e 188and 189.Cm f 190formats, or the maximum number of characters to be printed 191from a string; if the digit string is missing, the precision is treated 192as zero; 193.It Format: 194A character which indicates the type of format to use (one of 195.Cm diouxXfwEgGcsb ) . 196.El 197.Pp 198A field width or precision may be 199.Sq Cm \&* 200instead of a digit string. 201In this case an 202.Ar argument 203supplies the field width or precision. 204.Pp 205The format characters and their meanings are: 206.Bl -tag -width Fl 207.It Cm diouXx 208The 209.Ar argument 210is printed as a signed decimal (d or i), unsigned octal, unsigned decimal, 211or unsigned hexadecimal (X or x), respectively. 212.It Cm f 213The 214.Ar argument 215is printed in the style `[\-]ddd.ddd' where the number of d's 216after the decimal point is equal to the precision specification for 217the argument. 218If the precision is missing, 6 digits are given; if the precision 219is explicitly 0, no digits and no decimal point are printed. 220.It Cm eE 221The 222.Ar argument 223is printed in the style 224.Cm e 225.Sm off 226.Sq Op - Ar d.ddd No \(+- Ar dd 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 c 243The first character of 244.Ar argument 245is printed. 246.It Cm s 247Characters from the string 248.Ar argument 249are printed until the end is reached or until the number of characters 250indicated by the precision specification is reached; however if the 251precision is 0 or missing, all characters in the string are printed. 252.It Cm b 253As for 254.Cm s , 255but interpret character escapes in backslash notation in the string 256.Ar argument . 257.It Cm \&% 258Print a `%'; no argument is used. 259.El 260.Pp 261The decimal point 262character is defined in the program's locale (category 263.Dv LC_NUMERIC ) . 264.Pp 265In no case does a non-existent or small field width cause truncation of 266a field; padding takes place only if the specified field width exceeds 267the actual width. 268.Sh DIAGNOSTICS 269.Ex -std 270.Sh COMPATIBILITY 271The traditional 272.Bx 273behavior of converting arguments of numeric formats not beginning 274with a digit to the ASCII code of the first characer is not supported. 275.Sh SEE ALSO 276.Xr echo 1 , 277.Xr printf 3 278.Sh STANDARDS 279The 280.Nm 281command is expected to be compatible with the 282.St -p1003.2 283specification. 284.Sh HISTORY 285The 286.Nm 287command appeared in 288.Bx 4.3 Reno . 289It is modeled 290after the standard library function, 291.Xr printf 3 . 292.Sh BUGS 293Since the floating point numbers are translated from 294.Tn ASCII 295to floating-point and 296then back again, floating-point precision may be lost. 297.Pp 298.Tn ANSI 299hexadecimal character constants were deliberately not provided. 300.Pp 301The escape sequence \e000 is the string terminator. When present in the 302.Ar format , 303the 304.Ar format 305will be truncated at the \e000 character. 306