Thanks for the responses

As mentioned in original post, I preset the executables I need to run using the following approach:-

I have a hash which has the list of commands that can only be used. Something like..

my %commands = (
        opt1  => exe1,
        opt2 => exe2,
        opt3 => exe3,
    );
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In the CGI script, I have a variable , $runmode, which can take a value of 'opt1' or 'opt2' or 'opt3'. I retrieve the executable by $commands{ 'opt1' } and pass it on to the shell script.

I don't do any admin activities such as adding new user, deleting or modifying existing user accounts, etc.. using CGI scripts.