1.\" Copyright (c) 1990, 1991, 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 American National Standards Committee X3, on Information 6.\" Processing Systems. 7.\" 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in the 15.\" documentation and/or other materials provided with the distribution. 16.\" 3. All advertising materials mentioning features or use of this software 17.\" must display the following acknowledgement: 18.\" This product includes software developed by the University of 19.\" California, Berkeley and its contributors. 20.\" 4. Neither the name of the University nor the names of its contributors 21.\" may be used to endorse or promote products derived from this software 22.\" without specific prior written permission. 23.\" 24.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34.\" SUCH DAMAGE. 35.\" 36.\" @(#)rand.3 8.1 (Berkeley) 6/4/93 37.\" $FreeBSD$ 38.\" 39.Dd May 25, 1999 40.Dt RAND 3 41.Os 42.Sh NAME 43.Nm rand , 44.Nm srand , 45.Nm sranddev , 46.Nm rand_r 47.Nd bad random number generator 48.Sh LIBRARY 49.Lb libc 50.Sh SYNOPSIS 51.Fd #include <stdlib.h> 52.Ft void 53.Fn srand "unsigned seed" 54.Ft void 55.Fn sranddev void 56.Ft int 57.Fn rand void 58.Ft int 59.Fn rand_r "unsigned *ctx" 60.Sh DESCRIPTION 61.Bf -symbolic 62These interfaces are obsoleted by random(3). 63.Ef 64.Pp 65The 66.Fn rand 67function computes a sequence of pseudo-random integers in the range 68of 0 to 69.Dv RAND_MAX 70(as defined by the header file 71.Aq Pa stdlib.h ) . 72.Pp 73The 74.Fn srand 75function sets its argument 76.Fa seed 77as the seed for a new sequence of 78pseudo-random numbers to be returned by 79.Fn rand . 80These sequences are repeatable by calling 81.Fn srand 82with the same seed value. 83.Pp 84If no 85.Fa seed 86value is provided, the functions are automatically 87seeded with a value of 1. 88.Pp 89The 90.Fn sranddev 91function initializes a seed using the 92.Xr random 4 93random number device which returns good random numbers, 94suitable for cryptographic use. 95.Pp 96.Fn rand_r 97provides the same functionality as 98.Fn rand . 99A pointer to the context value 100.Fa ctx 101must be supplied by the caller. 102.Sh SEE ALSO 103.Xr random 3 , 104.Xr random 4 105.Sh STANDARDS 106The 107.Fn rand 108and 109.Fn srand 110functions 111conform to 112.St -isoC . 113.Pp 114The 115.Fn rand_r 116function is as proposed in the POSIX.4a Draft #6 document. 117