nginx上的PHP exec函数无法识别系统环境变量

Question

I try to use exec function in PHP to compile a source file with gcc with the following code.

<?php
exec("gcc -o hello hello.c 2>&1", $output, $return_value);
echo $output[0];

I got the following output when calling via web browser (I use nginx as a web server).

gcc: error trying to exec 'cc1': execvp: No such file or directory

However, if I run gcc -o hello hello.c on the command shell directly or call with php my_file.php on the shell directly, both ways compile successfully.

If I append the absolute path to gcc in my PHP code like this:

<?php
exec("/usr/bin/gcc -o hello hello.c 2>&1", $output, $return_value);
echo $output[0];

I got the following output.

collect2: fatal error: cannot find 'ld'

So, I think the problem is my webserver (nginx) doesn't know the system path environment variable to find /usr/bin which gcc and other gcc-dependencies resides in.

How can I let PHP exec function recognize system environment variables on nginx?

OS: Ubuntu 14.04

nginx: 1.6.2

PHP 5.5.9

Answer 1

I'm stuck on the same problem (exactly the same...) using nginx 1.10 and PHP 5.6 on Arch Linux. The same PHP code was working on Apache/Debian. When trying the Arch/Nginx server, I had the cc1 error... I replaced gcc by /usr/bin/gcc.... and I am now stuck on "collect2: fatal error: cannot find 'ld'"

The same compilation works with a shell... and ld is in /usr/bin. It just does not work when using "exec" in PHP.

Not satisfying (but working...) solution

By running gcc -v .....(just add -v to your compilation line) I could see :

...
COLLECT_GCC_OPTIONS='-v' '-D' 'exit=noexit' '-D' '_exit=noexit' ...
 /usr/lib/gcc/x86_64-pc-linux-gnu/6.1.1/collect2 -plugin ... (<= very long line)
collect2: fatal error: cannot find 'ld'

Then I did :

cd /usr/lib/gcc/x86_64-pc-linux-gnu/6.1.1/  # <- path to collect2 (see above)
ln -s /usr/bin/ld ld

Now ld prog is available in the same dir as collect2. And it works.

I am now looking for a better solution... :)