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chapter11/random_number.ksh

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+#!/usr/bin/ksh
+#
+# AUTHOR: Randy Micahel
+# SCRIPT: random_number.ksh
+# DATE: 11/12/2007
+# REV: 1.2.P
+#
+# PLATFORM: Not Platform Dependent
+#
+# EXIT CODES:
+#		0 - Normal script execution
+#		1 - Usage error
+#
+# REV LIST:
+#
+#
+# set -x # Uncomment to debug
+# set -n # Uncomment to check syntax without any command execution
+#
+####################################################
+########## DEFINE FUNCTIONS HERE ###################
+####################################################
+
+function usage
+{
+echo "\nUSAGE: $SCRIPT_NAME [-f] [upper_number_range]"
+echo "\nEXAMPLE: $SCRIPT_NAME"
+echo "Will return a random number between 0 and 32767" 
+echo "\nEXAMPLE: $SCRIPT_NAME 1000"
+echo "Will return a random number between 1 and 1000"
+echo "\nEXAMPLE: $SCRIPT_NAME -f 1000"
+echo "Will add leading zeros to a random number from"
+echo "1 to 1000, which keeps the number of digits consistant\n"
+}
+
+####################################################
+
+function get_random_number
+{
+# This function gets the next random number from the
+# $RANDOM variable. The range is 0 to 32767.
+
+echo "$RANDOM"
+}
+
+####################################################
+
+function in_range_random_number
+{
+# Create a pseudo-random number less than or equal
+# to the $UPPER_LIMIT value, which is user defined
+
+RANDOM_NUMBER=$(($RANDOM % $UPPER_LIMIT + 1))
+
+echo "$RANDOM_NUMBER"
+}
+
+####################################################
+
+function in_range_fixed_length_random_number_typeset
+{
+# Create a pseudo-random number less than or equal
+# to the $UPPER_LIMIT value, which is user defined.
+# This function will also pad the output with leading
+# zeros to keep the number of digits consistent using
+# the typeset command.
+
+# Find the length of each character string
+
+UL_LENGTH=$(echo ${#UPPER_LIMIT})
+
+# Fix the length of the RANDOM_NUMBER variable to
+# the length of the UPPER_LIMIT variable, specified
+# by the $UL_LENGTH variable.
+
+typeset -Z$UL_LENGTH RANDOM_NUMBER
+
+# Create a fixed length pseudo-random number
+
+RANDOM_NUMBER=$(($RANDOM % $UPPER_LIMIT + 1))
+
+# Return the value of the fixed length $RANDOM_NUMBER
+
+echo $RANDOM_NUMBER
+}
+
+####################################################
+############## BEGINNING OF MAIN ###################
+####################################################
+
+SCRIPT_NAME=`basename $0`
+
+RANDOM=$$  # Initialize the RANDOM environment variable
+           # using the PID as the initial seed
+
+case $# in
+0)   get_random_number
+;;
+
+1)  UPPER_LIMIT="$1"
+
+    # Test to see if $UPPER_LIMIT is a number
+
+    case $UPPER_LIMIT in
+    +([0-9])) :    # Do Nothing...It's a number
+                   # NOTE: A colon (:) is a no-op in Korn shell
+            ;;
+    *)        echo "\nERROR: $UPPER_LIMIT is not a number..."
+              usage
+              exit 1
+            ;;
+    esac
+ 
+    in_range_random_number
+;;
+
+2)  # Check for the -f switch to fix the length.
+
+    if [[ $1 = '-f' ]] || [[ $1 = '-F' ]]
+    then
+
+         UPPER_LIMIT="$2"
+
+         # Test to see if $UPPER_LIMIT is a number
+
+         case $UPPER_LIMIT in
+         +([0-9])) :    # Do Nothing...It's a number
+                        # NOTE: A colon (:) is a no-op in Korn shell
+               ;;
+         *)        echo "\nERROR: $UPPER_LIMIT is not a number..."
+                   usage
+                   exit 1
+               ;;
+         esac
+
+         in_range_fixed_length_random_number_typeset
+
+    else 
+         echo "\nInvalid argument $1, see usage below..."
+         usage
+         exit 1
+    fi
+;;
+
+*)  usage
+    exit 1
+;;
+esac
+
+# End of random_number.ksh Shell Script