BASH – Generate a Random String

BASH – Generate a Random String

In a recent project, I needed a function that would generate a random string for me. In my case, I was creating a random file name to store some data, but there are other uses as well, so I am posting the BASH code here in the hope that it will help others out there on the net writing BASH scripts and need a good random string function:

#!/bin/bash
function randomString {
        # if a param was passed, it's the length of the string we want
        if [[ -n $1 ]]; then
                local myStrLength=$1;
        else
                # otherwise set to default
                local myStrLength=16;
        fi

        # create character set, update this as needed
         charSet="abcdefghijklmonpqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-_^!"

        myRandomString="";
        for i in `seq 1 $myStrLength`; do
              char=${charSet:$RANDOM % ${#charSet}:1}
              myRandomString+=$char
        done
}

randomString $1;
echo $myRandomString;

Save this to a script file (I called mine rand.sh) using the command-line ‘nano’ editor:

me@home:~ $ nano rand.sh

Now mark it as an executable script:

me@home:~ $ chmod +x rand.sh

And now you should be able to run it and pass it whatever you want as the length of your string:

me@home:~ $ ./rand.sh
Bo82z3duWs8yQ0^6
me@home:~ $ ./rand.sh 32
!pP2XWleIwhm7QosN8m5u4wxmXS!eykn
me@home:~ $ ./rand.sh 64
TYv4CDwimTzMdDkQ7FhmXMs7XbHNoF9eVhxN2_n9!1e0wbWaMzDAGs!RuPbPjlWT
me@home:~ $ ./rand.sh 256
svfUuvyxMt1ZBkNmTNnWR!HRlrj-d7YUDluxUMbD^qCkdZ2whC58dGXKv3!9dWIUE6a0WuvGy3nWXmizzW_-5TVWOjotIQbmB7Uf2p5f^HMh49gLTeCBHTGYnU8XJQ8XetFcohKw-_eGfBuZTHGncuZNn-yd8TBH9F49fCbQH!Vw^r5XrRuCl1-X15WXubLy!ojVLNUxzE^lXICzQSF22Ci1WGBUxzAwONvKBqFe^m3_3ZSjFXZbxizxSzY6M6w^

Hope this helps someone!

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