1.\" 2.\" Copyright (c) 2001 Andrew R. Reiter 3.\" Copyright (c) 2004 Joerg Wunsch 4.\" All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 15.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 16.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 19.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 20.\" BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 21.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 22.\" AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 23.\" OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25.\" SUCH DAMAGE. 26.\" 27.\" $FreeBSD$ 28.\" 29.Dd April 14, 2023 30.Dt PRINTF 9 31.Os 32.Sh NAME 33.Nm printf , 34.Nm uprintf , 35.Nm tprintf , 36.Nm log 37.Nd formatted output conversion 38.Sh SYNOPSIS 39.In sys/types.h 40.In sys/systm.h 41.Ft int 42.Fn printf "const char *fmt" ... 43.Ft void 44.Fn tprintf "struct proc *p" "int pri" "const char *fmt" ... 45.Ft int 46.Fn uprintf "const char *fmt" ... 47.Ft int 48.Fn vprintf "const char *fmt" "va_list ap" 49.In sys/syslog.h 50.Ft void 51.Fn log "int pri" "const char *fmt" ... 52.Ft void 53.Fn vlog "int pri" "const char *fmt" "va_list ap" 54.Sh DESCRIPTION 55The 56.Nm 57family of functions are similar to the 58.Xr printf 3 59family of functions. 60The different functions each use a different output stream. 61The 62.Fn uprintf 63function outputs to the current process' controlling tty, while 64.Fn printf 65writes to the console as well as to the logging facility. 66The 67.Fn tprintf 68function outputs to the tty associated with the process 69.Fa p 70and the logging facility if 71.Fa pri 72is not \-1. 73The 74.Fn log 75function sends the message to the kernel logging facility, using 76the log level as indicated by 77.Fa pri , 78and to the console if no process is yet reading the log. 79.Pp 80Each of these related functions use the 81.Fa fmt 82parameter in the same manner as 83.Xr printf 3 . 84However, 85.Nm 86adds two other conversion specifiers and omits one. 87.Pp 88The 89.Cm \&%b 90identifier expects two arguments: an 91.Vt int 92and a 93.Vt "char *" . 94These are used as a register value and a print mask for decoding bitmasks. 95The print mask is made up of two parts: the base and the 96arguments. 97The base value is the output base expressed as an integer value; 98for example, \e10 gives octal and \e20 gives hexadecimal. 99The arguments are made up of a sequence of bit identifiers. 100Each bit identifier begins with an integer value which is the number of the 101bit (starting from 1) this identifier describes. 102The rest of the identifier is a string of characters containing the name of 103the bit. 104The string is terminated by either the bit number at the start of the next 105bit identifier or 106.Dv NUL 107for the last bit identifier. 108.Pp 109The 110.Cm \&%D 111identifier is meant to assist in hexdumps. 112It requires two arguments: a 113.Vt "u_char *" 114pointer and a 115.Vt "char *" 116string. 117The memory pointed to by the pointer is output in hexadecimal one byte at 118a time. 119The string is used as a delimiter between individual bytes. 120If present, a width directive will specify the number of bytes to display. 121By default, 16 bytes of data are output. 122.Pp 123The 124.Cm \&%n 125conversion specifier is not supported. 126.Pp 127The 128.Fn log 129function uses 130.Xr syslog 3 131level values 132.Dv LOG_DEBUG 133through 134.Dv LOG_EMERG 135for its 136.Fa pri 137parameter (mistakenly called 138.Sq priority 139here). 140Alternatively, if a 141.Fa pri 142of \-1 is given, the message will be appended to the last log message 143started by a previous call to 144.Fn log . 145As these messages are generated by the kernel itself, the facility will 146always be 147.Dv LOG_KERN . 148.Sh RETURN VALUES 149The 150.Fn printf 151and the 152.Fn uprintf 153functions return the number of characters displayed. 154.Sh EXAMPLES 155This example demonstrates the use of the 156.Cm \&%b 157and 158.Cm \&%D 159conversion specifiers. 160The function 161.Bd -literal -offset indent 162void 163printf_test(void) 164{ 165 166 printf("reg=%b\en", 3, "\e10\e2BITTWO\e1BITONE"); 167 printf("out: %4D\en", "AAZZ", ":"); 168} 169.Ed 170.Pp 171will produce the following output: 172.Bd -literal -offset indent 173reg=3<BITTWO,BITONE> 174out: 41:41:5a:5a 175.Ed 176.Pp 177The call 178.Bd -literal -offset indent 179log(LOG_DEBUG, "%s%d: been there.\en", sc->sc_name, sc->sc_unit); 180.Ed 181.Pp 182will add the appropriate debug message at priority 183.Dq Li kern.debug 184to the system log. 185.Sh SEE ALSO 186.Xr printf 3 , 187.Xr syslog 3 188