examples/scripts.v2/bashrand

   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
   7 usage()
   8 {
   9         echo "$PROG: usage: $PROG [-s seed] lower-limit upper-limit" >&2
  10 }
  11
  12 PROG=${0##*/}
  13
  14 SEED=$$         # Initialize random-number seed value with PID
  15
  16 while getopts s: opt
  17 do
  18         case "$opt" in
  19         s)      SEED=$OPTARG ;;
  20         *)      usage ; exit 2 ;;
  21         esac
  22 done
  23
  24 shift $((OPTIND - 1))
  25
  26 # Process command-line arguments:
  27 case $# in
  28     2)  Lower=$1; Upper=$2 ;;
  29     *)  usage ; exit 2 ;;
  30 esac
  31
  32 # Check that specified values are integers:
  33 expr "$Lower" + 0 >/dev/null 2>&1 || {
  34         echo "$PROG: lower ($Lower) not an integer" >&2
  35         exit 1
  36 }
  37
  38 expr "$Upper" + 0 >/dev/null 2>&1 || {
  39         echo "$PROG: upper ($Upper) not an integer" >&2
  40         exit 1
  41 }
  42
  43 expr "$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:
  70 RANDOM=$SEED
  71
  72 # Compute value, scaled within range:
  73 let rand="$RANDOM % ($Upper - $Lower + 1) + $Lower"
  74
  75 # Report result:
  76 echo $rand