48 lines
1.1 KiB
Bash
48 lines
1.1 KiB
Bash
#!/bin/bash
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# seeding-random.sh: Seeding the RANDOM variable.
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MAXCOUNT=25 # How many numbers to generate.
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random_numbers ()
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{
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count=0
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while [ "$count" -lt "$MAXCOUNT" ]
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do
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number=$RANDOM
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echo -n "$number "
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let "count += 1"
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done
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}
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echo; echo
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RANDOM=1 # Setting RANDOM seeds the random number generator.
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random_numbers
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echo; echo
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RANDOM=1 # Same seed for RANDOM...
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random_numbers # ...reproduces the exact same number series.
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echo; echo
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RANDOM=2 # Trying again, but with a different seen...
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random_numbers # gives a different number series.
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echo; echo
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# RANDOM=$$ seeds RANDOM from process id of script.
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# It is also possible to seed RANDOM from 'time' or 'date'.
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# Getting fancy...
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SEED=$(head -1 /dev/urandom | od -N 1 | awk '{ print $2 }')
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# Pseudo-random output fetched from /dev/urandom (system pseudo-random "device"),
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# then converted to line of printable (octal) numbers by "od",
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# finally "awk" retrieves just one number for SEED.
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RANDOM=$SEED
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random_numbers
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echo; echo
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exit 0
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