URL Rewrite giving 500 internal error

I'm trying to perform a URL Rewrite but giving me a 500 Internal Server Error

I have an index.php file that can take a parameter which I called cmd so the URL should look like:

http://localhost/some_folder/index.php?cmd=some_parameter

What I'm trying to achieve is allowing users to just type any of the following:

http://localhost/some_folder/some_parameter

OR

http://localhost/some_folder/index/some_parameter

Here is my .htaccess file:

RewriteEngine On # Turn on the rewriting engineRewriteRule ^index.php/?$ index.php?cmd=shifts [NC,L]

I also tried:

Options +FollowSymLinksRewriteEngine onRewriteRule /cmd/(.*)/ index.php?cmd=$1

I don't know what I am doing wrong here!

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