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 April 25, 2023 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 an 99.Em octal 100value which is the number of the bit (starting from 1) this identifier 101describes. 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