You don't give much to go on; what do you mean by "the value doesn't work"?

My first guess though would be that the problem is here in the main routine:

    $user_name = em(param('name'));
    &file_creation($user_name);
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file_creation then converts $user_name as so:

    $user_name = substr($user_name, 1, 4);
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The em function prints an <EM> tag, so $user_name ends up containing "EM>" plus the first character of the parameter value.