1: php has many system predefined variables, which can easily determine whether the server system is windows or *unix, among which the related functions or predefined variables are as follows: php_uname(), PHP_OS, DIRECTORY_SEPARATOR, PHP_SHLIB_SUFFIX, PATH_SEPARATOR

2: Examples:

    <?php
        if(strtolower(substr(PHP_OS, 0, 3)) == 'win'){
            echo 'windows';
        }else{
            echo 'linux';
        }