1.\" $NetBSD: kprintf.9,v 1.12 2002/02/13 08:18:43 ross Exp $ 2.\" 3.\" Copyright (c) 1998 The NetBSD Foundation, Inc. 4.\" All rights reserved. 5.\" 6.\" This code is derived from software contributed to The NetBSD Foundation 7.\" by Jeremy Cooper. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 3. All advertising materials mentioning features or use of this software 18.\" must display the following acknowledgement: 19.\" This product includes software developed by the NetBSD 20.\" Foundation, Inc. and its contributors. 21.\" 4. Neither the name of The NetBSD Foundation nor the names of its 22.\" contributors may be used to endorse or promote products derived 23.\" from this software without specific prior written permission. 24.\" 25.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 26.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 27.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 28.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 29.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 30.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 31.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 32.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 33.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 34.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 35.\" POSSIBILITY OF SUCH DAMAGE. 36.\" 37.Dd September 1, 1998 38.Dt KPRINTF 9 39.Os 40.Sh NAME 41.Nm printf, snprintf, vprintf, vsnprintf, uprintf, ttyprintf, tprintf 42.Nd kernel formatted output conversion 43.Sh SYNOPSIS 44.Fd #include \*[Lt]sys/systm.h\*[Gt] 45.Ft void 46.Fn "printf" "const char *format" "..." 47.Ft int 48.Fn "snprintf" "char *buf" "size_t size" "const char *format" "..." 49.Ft void 50.Fn "vprintf" "const char *format" "va_list ap" 51.Ft int 52.Fn "vsnprintf" "char *buf" "size_t size" "const char *format" "va_list ap" 53.Ft void 54.Fn "uprintf" "const char *format" "..." 55.Ft void 56.Fn "ttyprintf" "struct tty *tty" "const char *format" "..." 57.Fd #include \*[Lt]sys/tprintf.h\*[Gt] 58.Ft tpr_t 59.Fn "tprintf_open" "struct proc *p" 60.Ft void 61.Fn "tprintf" "tpr_t tpr" "const char *format" "..." 62.Ft void 63.Fn "tprintf_close" "tpr_t tpr" 64.Sh DESCRIPTION 65The 66.Fn printf 67family of functions allows the kernel to send formatted messages to various 68output devices. 69The functions 70.Fn printf 71and 72.Fn vprintf 73send formatted strings to the system console. 74The functions 75.Fn snprintf 76and 77.Fn vsnprintf 78write output to a string buffer. These four functions work similarly 79to their user space counterparts, and are not described in detail here. 80.Pp 81The functions 82.Fn uprintf 83and 84.Fn ttyprintf 85send formatted strings to the current process's controlling tty and a specific 86tty, respectively. 87.Pp 88The 89.Fn tprintf 90function sends formatted strings to a process's controlling tty, 91via a handle of type tpr_t. 92This allows multiple write operations to the tty with a guarantee that the 93tty will be valid across calls. A handle is acquired by calling 94.Fn tprintf_open 95with the target process as an argument. This handle must be closed with 96a matching call to 97.Fn tprintf_close . 98.Sh RETURN VALUES 99The 100.Fn snprintf 101and 102.Fn vsnprintf 103functions return the number of characters placed in the buffer 104.Fa buf . 105.Sh SEE ALSO 106.Xr printf 1 , 107.Xr printf 3 , 108.Xr bitmask_snprintf 9 109.Sh CODE REFERENCES 110.Pa sys/kern/subr_prf.c 111.Sh HISTORY 112The 113.Fn sprintf 114and 115.Fn vsprintf 116unsized string formatting functions are supported for compatibility only, 117and are not documented here. New code should use the size-limited 118.Fn snprintf 119and 120.Fn vsnprintf 121functions instead. 122.Pp 123In 124.Nx 1.5 125and earlier, 126.Fn printf 127supported more format strings than the user space 128.Fn printf . 129These nonstandard format strings are no longer supported. For the 130functionality provided by the former 131.Li %b 132format string, see 133.Xr bitmask_snprintf 9 . 134.Sh BUGS 135The 136.Fn uprintf 137and 138.Fn ttyprintf 139functions should be used sparingly, if at all. Where multiple lines of 140output are required to reach a process's controlling terminal, 141.Fn tprintf 142is preferred. 143