为什么PHP exec（）命令没有运行？

Question

I have a very simple PHP script to try to use the exec command. The code is

 <?php
// outputs the username that owns the running php/httpd process
// (on a system with the "whoami" executable in the path)
echo("test<br>");
echo exec('whoami');
echo("test");
?>

However when I access the page, it just prints out:

test
test

It does not print the output from "whoami" command, which when run from command line displays

me

What is the problem here? I cannot work it out.

Thanks a lot!

Answer 1

(on a system with the "whoami" executable in the path)

PATH , like all environment variables, is not system-wide but ultimately per-process .

That is, though your typical bash session may well include the path to this executable in PATH , the environment in which your PHP script is running (say, an Apache CGI context) does not. This may be for any reason.

Provide an absolute path to whoami , instead.