1#! /bin/bash
2# bashrand - generate a random number in a specified range with an
3#	     optionally specified ``seed'' value.
4#
5# Original Author: Peter Turnbull, May 1993
6
7usage()
8{
9	echo "$PROG: usage: $PROG [-s seed] lower-limit upper-limit" >&2
10}
11
12PROG=${0##*/}
13
14SEED=$$         # Initialize random-number seed value with PID
15
16while getopts s: opt
17do
18	case "$opt" in
19	s)	SEED=$OPTARG ;;
20	*)	usage ; exit 2 ;;
21	esac
22done
23
24shift $((OPTIND - 1))
25
26# Process command-line arguments:
27case $# in
28    2)  Lower=$1; Upper=$2 ;;
29    *)  usage ; exit 2 ;;
30esac
31
32# Check that specified values are integers:
33expr "$Lower" + 0 >/dev/null 2>&1 || {
34	echo "$PROG: lower ($Lower) not an integer" >&2
35	exit 1
36}
37
38expr "$Upper" + 0 >/dev/null 2>&1 || {
39	echo "$PROG: upper ($Upper) not an integer" >&2
40	exit 1
41}
42
43expr "$SEED" + 0 >/dev/null 2>&1 || {
44	echo "$PROG: seed ($SEED) not an integer" >&2
45	exit 1
46}
47
48# Check that values are in the correct range:
49(( $Lower < 0 )) || [ `expr "$Lower" : '.*'` -gt 5 ] && {
50	echo "$PROG: Lower limit ($Lower) out of range" >&2
51	exit 1
52}
53
54(( $Upper > 32767 )) || [ `expr "$Upper" : '.*'` -gt 5 ] && {
55	echo "$PROG: Upper limit ($Upper) out of range" >&2;
56	exit 1
57}
58
59(( $SEED < 0 )) || (( $SEED > 32767 )) || [ `expr "$SEED" : '.*'` -gt 5 ] && {
60	echo "$PROG: Seed value ($SEED) out of range (0 to 32767)" >&2
61	exit 1
62}
63
64(( $Upper <= $Lower )) && {
65	echo "$PROG: upper ($Upper) <= lower value ($Lower)" >&2
66	exit 1
67}
68
69# Seed the random-number generator:
70RANDOM=$SEED
71
72# Compute value, scaled within range:
73let rand="$RANDOM % ($Upper - $Lower + 1) + $Lower"
74
75# Report result:
76echo $rand
77