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.Dd December 19, 2025 28.Dt PRINTF 9 29.Os 30.Sh NAME 31.Nm printf , 32.Nm uprintf , 33.Nm tprintf , 34.Nm log 35.Nd formatted output conversion 36.Sh SYNOPSIS 37.In sys/types.h 38.In sys/systm.h 39.Ft int 40.Fn printf "const char *fmt" ... 41.Ft void 42.Fn tprintf "struct proc *p" "int pri" "const char *fmt" ... 43.Ft int 44.Fn uprintf "const char *fmt" ... 45.Ft int 46.Fn vprintf "const char *fmt" "va_list ap" 47.In sys/syslog.h 48.Ft void 49.Fn log "int pri" "const char *fmt" ... 50.Ft void 51.Fn vlog "int pri" "const char *fmt" "va_list ap" 52.Sh DESCRIPTION 53The 54.Nm 55family of functions are similar to the 56.Xr printf 3 57family of functions. 58The different functions each use a different output stream. 59The 60.Fn uprintf 61function outputs to the current process' controlling tty, while 62.Fn printf 63writes to the console as well as to the logging facility. 64The 65.Fn tprintf 66function outputs to the tty associated with the process 67.Fa p 68and the logging facility if 69.Fa pri 70is not \-1. 71The 72.Fn log 73function sends the message to the kernel logging facility, using 74the log level as indicated by 75.Fa pri , 76and to the console if no process is yet reading the log. 77.Pp 78Each of these related functions use the 79.Fa fmt 80parameter in the same manner as 81.Xr printf 3 . 82However, 83.Nm 84adds two other conversion specifiers and omits one. 85.Pp 86The 87.Cm \&%b 88identifier expects two arguments: an 89.Vt int 90and a 91.Vt "char *" . 92These are used as a register value and a print mask for decoding bitmasks. 93The print mask is made up of two parts: the base and the 94arguments. 95The base value is the output base (radix) expressed as an octal value; 96for example, \e10 gives octal and \e20 gives hexadecimal. 97The arguments are made up of a sequence of bit identifiers. 98Each bit identifier begins with a character specifying the number of the bit 99(starting from 1) this identifier describes. 100The characters from \e01 to \e40 can be used to specify bit numbers in the 101range from 1 to 32 and characters from \e200 to \e377 to specify bit numbers 102in the range from 1 to 128. 103The rest of the identifier is a string of characters containing the name of 104the bit. 105The identifier is terminated by either the bit number at the start of the next 106bit identifier or by 107.Dv NUL 108for the last bit identifier. 109.Pp 110The 111.Cm \&%D 112identifier is meant to assist in hexdumps. 113It requires two arguments: a 114.Vt "u_char *" 115pointer and a 116.Vt "char *" 117string. 118The memory pointed to by the pointer is output in hexadecimal one byte at 119a time. 120The string is used as a delimiter between individual bytes. 121If present, a width directive will specify the number of bytes to display. 122By default, 16 bytes of data are output. 123.Pp 124The 125.Cm \&%n 126conversion specifier is not supported. 127.Pp 128The 129.Fn log 130function uses 131.Xr syslog 3 132level values 133.Dv LOG_DEBUG 134through 135.Dv LOG_EMERG 136for its 137.Fa pri 138parameter (mistakenly called 139.Sq priority 140here). 141Alternatively, if a 142.Fa pri 143of \-1 is given, the message will be appended to the last log message 144started by a previous call to 145.Fn log . 146As these messages are generated by the kernel itself, the facility will 147always be 148.Dv LOG_KERN . 149.Sh RETURN VALUES 150The 151.Fn printf 152and the 153.Fn uprintf 154functions return the number of characters displayed. 155.Sh EXAMPLES 156This example demonstrates the use of the 157.Cm \&%b 158and 159.Cm \&%D 160conversion specifiers. 161The function 162.Bd -literal -offset indent 163void 164printf_test(void) 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 same output will be generated by the following function: 178.Bd -literal -offset indent 179void 180printf_test(void) 181{ 182 printf("reg=%b\en", 3, "\e10\e201BITTWO\e200BITONE"); 183 printf("out: %4D\en", "AAZZ", ":"); 184} 185.Ed 186.Pp 187The call 188.Bd -literal -offset indent 189log(LOG_DEBUG, "%s%d: been there.\en", sc->sc_name, sc->sc_unit); 190.Ed 191.Pp 192will add the appropriate debug message at priority 193.Dq Li kern.debug 194to the system log. 195.Sh SEE ALSO 196.Xr printf 3 , 197.Xr syslog 3 198