PHP exec() vs system() vs passthru()

Question

What are the differences?

Is there a specific situation or reason for each function? If yes, can you give some examples of those situations?

PHP.net says tha

Answer 1

They have slightly different purposes.

• exec() is for calling a system command, and perhaps dealing with the output yourself.
• system() is for executing a system command and immediately displaying the output - presumably text.
• passthru() is for executing a system command which you wish the raw return from - presumably something binary.

Regardless, I suggest you not use any of them. They all produce highly unportable code.