The difference between exec and popen

Question

I want to run an external PHP file on my server I found out that I can use either exec or popen.

I read that popen is used for Windows while, exec is used for Linux.

On the other hand I saw examples where popen can also be used for Linux. I am still a newbie. Is it possible? Which do you recommend for Linux if both exec and popen work?

Kindly what are the advantages as I am still confused.

Answer 1

If you just need to exec an external app, use exec() or shell_exec(). popen() is used if you need a pointer, which is something similar to what fopen() does with files. fopen() just opens the pointer to file, nothing else. Then you need other functions (fread(), fwrite()) to actually work with the file.

The same logic applies to popen().

exec() or shell_exec() can be used on windows as well as linux.

Answer 2

In my case, I am using popen to run asynchronous php script from an Apache web app. I was trying exec, shell_exec and pclose(popen(...)) and the only one that creates a new process and execute it asynchronously is popen. All the others wait for the script to be finish before answering to browser.

My configuration is CentOS7, PHP 5.4.16 and Apache 2.4, haven't tried on Windows.