3 * The Regents of the University of California. All rights reserved.
5 * This code is derived from software contributed to Berkeley by
6 * Guy Harris at Network Appliance Corp.
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
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.
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
38 static const char copyright[] =
39 "@(#) Copyright (c) 1994\n\
40 The Regents of the University of California. All rights reserved.\n";
45 static char sccsid[] = "@(#)random.c 8.5 (Berkeley) 4/5/94";
47 static const char rcsid[] =
51 #include <sys/types.h>
61 void usage __P((void));
69 int ch, random_exit, selected, unbuffer_output;
72 random_exit = unbuffer_output = 0;
74 while ((ch = getopt(argc, argv, "er")) != -1)
97 denom = strtod(*argv, &ep);
100 if (denom <= 0 || *ep != '\0')
101 errx(1, "denominator is not valid.");
102 if (random_exit && denom > 255)
103 errx(1, "denominator must be <= 255 for random exit.");
112 /* Compute a random exit status between 0 and denom - 1. */
114 return ((denom * random()) / LONG_MAX);
117 * Act as a filter, randomly choosing lines of the standard input
118 * to write to the standard output.
121 setbuf(stdout, NULL);
124 * Select whether to print the first line. (Prime the pump.)
125 * We find a random number between 0 and denom - 1 and, if it's
126 * 0 (which has a 1 / denom chance of being true), we select the
129 selected = (int)(denom * random() / LONG_MAX) == 0;
130 while ((ch = getchar()) != EOF) {
134 /* End of that line. See if we got an error. */
138 /* Now see if the next line is to be printed. */
139 selected = (int)(denom * random() / LONG_MAX) == 0;
151 (void)fprintf(stderr, "usage: random [-er] [denominator]\n");