shell实例(九) ---随机数

1.两个指定值之间的随机数

#! /bin/sh
randomBetween() {
 syntax() {
   echo
   echo "Syntax: randomBetween [min] [max] [multiple] "
   echo
   echo "Expects up to 3 passed parameters, but all are completely optional."
   echo "min is the minimum value"
   echo "max is the maximum value"
   echo "multiple specifies that the answer must be a multiple of this value."
   echo "   i.e answer must be evenly divisible by this number."
   echo
   echo "If any value is missing,defaults area supplied as : 0 32767 1"
   echo "Successful completion returns 0,unsuccessful completion returns."
   echo "function syntax and 1."
   echo "The answer is returned in the global variable random Between Answer"
   echo "Negative values for any passed parameter are handled correctly."
}

local min={1:-0}
local max={2:-32767}
local divisibleBy=${3:-1}

local x
local spread

[ ${divisibleBy} -lt 0 ] && divisibleBy=$((0-divisibleBy))

if [ $# -gt 3 -o ${divisibleBy} -eq 0 -o ${min} -eq ${max} ]
then
  systax
  return 1
fi

if [ ${min} -gt ${max} ]
then
  x=${min}
  min=${max}
  max=${x}
fi

if [ $((min/divisibleBy*divisibleBy)) -ne ${min} ]
then
  if [ ${min} -lt 0 ]
  then
    min=$((min/
[root@localhost yjg]# vi 9-27.sh

 syntax() {
   echo
   echo "Syntax: randomBetween [min] [max] [multiple] "
   echo
   echo "Expects up to 3 passed parameters, but all are completely optional."
   echo "min is the minimum value"
   echo "max is the maximum value"
   echo "multiple specifies that the answer must be a multiple of this value."
   echo "   i.e answer must be evenly divisible by this number."
   echo
   echo "If any value is missing,defaults area supplied as : 0 32767 1"
   echo "Successful completion returns 0,unsuccessful completion returns."
   echo "function syntax and 1."
   echo "The answer is returned in the global variable random Between Answer"
   echo "Negative values for any passed parameter are handled correctly."
}

local min={1:-0}
local max={2:-32767}
local divisibleBy=${3:-1}

local x
local spread

[ ${divisibleBy} -lt 0 ] && divisibleBy=$((0-divisibleBy))

if [ $# -gt 3 -o ${divisibleBy} -eq 0 -o ${min} -eq ${max} ]
then
  systax
  return 1
fi

if [ ${min} -gt ${max} ]
then
  x=${min}
  min=${max}
  max=${x}
fi

if [ $((min/divisibleBy*divisibleBy)) -ne ${min} ]
then
  fi
  if [ ${min} -lt 0 ]
  then
    min=$((min/divisibleBy*divisibleBy))
  else
    min=$((((min/divisibleBy)+1)*divisibleBy))
  fi
fi

if [ $((max/divisibleBy*divisibleBy)) -ne ${max} ]
then
  if [ ${max} -lt 0 ]
  then
    max=$((((max/divisibleBy)-1)*divisibleBy))
  else
   max=$((max/divisibleBy*divisibleBy))
  fi
fi

spread=$((max-min))
[ ${spread} -lt 0 ] && spread=$((0-spread))
let spread+=divisibleBy
randomBetweenAnswer=$(((RANDOM%spread)/divisibleBy*divisibleBy+min))
return 0
}

min=-14
max=20
divisibleBy=3

declare -a answer
minimum=${min}
maximum=${max}
if [ $((minimum/divisibleBy*divisibleBy)) -ne ${minimum} ]
then
  if [ ${minimum} -lt 0 ]
  then
    minimum=$((minimum/divisibleBy*divisibleBy))
  else
    minimum=$((((minimum/divisibleBy)+1)*divisibleBy))
  fi
fi

if [ $((maximum/divisibleBy*divisibleBy)) -ne ${maximum} ]
then
  if [ ${maximum} -lt 0 ]
  then
    maximum=$((((maximum/divisibleBy)-1)*divisibleBy))
  else
    maximum=$((maximum/divisibleBy*divisibleBy))
  fi
fi

displacement=$((0-minimum))
for (( i=${minimum}; i<=${maximum}; i+=divisibleBy))
do
 answer[i+displacement]=0
done

loopIt=1000
for ((i=0; i<${loopIt}; ++i))
do
  randomBetween ${max} ${min} ${divisibleBy}
  [ ${randomBetweenAnswer} -lt ${min} -o ${randomBetweenAnswer} -gt ${max} ] && echo MIN or MAX error --- ${randomBetweenAnswer}!
  [ ${randomBetweenAnswer%${divisibleBy})) -ne 0 ] && echo DIVISIBLE By error -- ${randomBetweenAnswer}!
  answer[randomBetweenAnswer+displacement]=$((answer[randomBetweenAnswer+displacement]+1))
done

for ((i=${minimum}; i<=${maximum}; i+=divisibleBy))
do
  [ ${answer[i+displacement]} -eq 0 ] && echo "We never got an answer of $i." || echo "${i} occurred ${answer[i+displacement]} times
."
done

exit 0

 

2.用随机数来摇单个骰子

#! /bin/sh
RANDOM=$$
PIPS=6
MAXTHROWS=6
throw=0

ones=0
twos=0
threes=0
fours=0
fives=0
sixes=0

print_result(){
 echo
 echo "ones = $ones"
 echo "twos = $twos"
 echo "threes = $threes"
 echo "fours = $fours"
 echo "fives = $fives"
 echo "sixes = $sixes"
 echo
}

update_count(){
 echo "update_count: $1"
 case "$1" in
 0) let "ones += 1";;
 1) let "twos += 1";;
 2) let "threes += 1";;
 3) let "fours += 1";;
 4) let "fives += 1";;
 5) let "sixes += 1";;
esac
}

echo

while [ "$throw" -lt  "$MAXTHROWS" ]
do
 let "die1 = RANDOM % $PIPS"
 update_count $die1
 let "throw += 1"
 print_result
done

#print_result
exit 0

 

3.重新分配随机数种子

#! /bin/sh
MAXCOUNT=25
random_numbers(){
count=0
while [ "$count" -lt "$MAXCOUNT" ]
do
 number=$RANDOM
 echo -n "$number "
 let "count += 1"
done
}

echo;echo

RANDOM=1
random_numbers
echo;echo

RANDOM=1
random_numbers

echo;echo

RANDOM=2
random_numbers

echo;echo
SEED=$(head -l /dev/urandom | od -N 1 | awk '{ print $2 }')
RANDOM=$SEED
random_numbers

echo;echo
exit 0

 

4.使用awk来产生伪随机数

#! /bin/sh
AWKSCRIPT=' { srand(); print rand() } '    --------srand()是生成伪随机数函数
echo -n "Random number between 0 and 1 = "
echo | awk "$AWKSCRIPT"
exit 0