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There are a number of reasons why you may want to generate a random number in a Bash shell. We are referring to a Bash shell rather than using a programming language such as C++, Java or Python.

Maybe you want to pull a random line from a file.

Maybe you want to generate a random filename.

Maybe you want to get a number for a simple dice game.

Maybe you are playing a guessing game. Maybe you are picking team members and you need a random number for each player.

Whatever it is, it can be done.

Built into the Bash shell, there is a random number generator. It is called $RANDOM. This is a function, not a constant (note the dollar sign in front of the word). Try running the following command:

echo $RANDOM

This will return an integer from 0 to 32767. You can limit the scope of this number if you put a constraint by using a modulo.

echo $(( RANDOM % 10 ))

This will return a number between 0 to 9. Depending on the purpose of the number, zero may not be suitable for your case. Ten is also not included. You can shift one by adding one number.

echo $(( 1 + RANDOM % 10 ))

Rather than returning a number between 0 to 9, this will return a number between 1 to 10. You are adding a one to whatever number is given.

Tim Miller

Tim has always been obsessed with computers his whole life. After working for 25 years in the computer and electronics field, he now enjoys writing about computers to help others. Most of his time is spent in front of his computer or other technology to continue to learn more. He likes to try new things and keep up with the latest industry trends so he can share them with others.

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