mirror of https://github.com/tLDP/LDP
101 lines
1.9 KiB
Bash
101 lines
1.9 KiB
Bash
#!/bin/bash
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# $RANDOM returns a different random integer at each invocation.
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# Nominal range: 0 - 32767 (signed 16-bit integer).
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MAXCOUNT=10
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count=1
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echo
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echo "$MAXCOUNT random numbers:"
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echo "-----------------"
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while [ "$count" -le $MAXCOUNT ] # Generate 10 ($MAXCOUNT) random integers.
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do
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number=$RANDOM
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echo $number
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let "count += 1" # Increment count.
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done
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echo "-----------------"
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# If you need a random int within a certain range, use the 'modulo' operator.
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# This returns the remainder of a division operation.
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RANGE=500
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echo
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number=$RANDOM
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let "number %= $RANGE"
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echo "Random number less than $RANGE --- $number"
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echo
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# If you need a random int greater than a lower bound,
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# then set up a test to discard all numbers below that.
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FLOOR=200
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number=0 #initialize
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while [ "$number" -le $FLOOR ]
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do
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number=$RANDOM
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done
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echo "Random number greater than $FLOOR --- $number"
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echo
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# May combine above two techniques to retrieve random number between two limits.
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number=0 #initialize
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while [ "$number" -le $FLOOR ]
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do
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number=$RANDOM
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let "number %= $RANGE" # Scales $number down within $RANGE.
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done
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echo "Random number between $FLOOR and $RANGE --- $number"
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echo
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# Generate binary choice, that is, "true" or "false" value.
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BINARY=2
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number=$RANDOM
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T=1
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let "number %= $BINARY"
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# let "number >>= 14" gives a better random distribution
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# (right shifts out everything except last binary digit).
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if [ "$number" -eq $T ]
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then
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echo "TRUE"
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else
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echo "FALSE"
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fi
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echo
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# May generate toss of the dice.
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SPOTS=7 # Modulo 7 gives range 0 - 6.
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DICE=2
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ZERO=0
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die1=0
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die2=0
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# Tosses each die separately, and so gives correct odds.
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while [ "$die1" -eq $ZERO ] # Can't have a zero come up.
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do
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let "die1 = $RANDOM % $SPOTS" # Roll first one.
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done
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while [ "$die2" -eq $ZERO ]
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do
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let "die2 = $RANDOM % $SPOTS" # Roll second one.
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done
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let "throw = $die1 + $die2"
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echo "Throw of the dice = $throw"
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echo
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exit 0
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