Execution failing while running from browser - php

Question

I am building online compiler for C and C++ using php, so we are using gcc compiler to execute using "shell_exec" function ,
test.php
<?php
$output = shell_exec("gcc /var/www/test/main.c 2>&1");
print_R($output);
?>
If I execute in terminal like php test.php, is working fine and it is creating a.out compiled file.
But If I try to run in the browser like localhost/test.php, its giving below error
gcc: error trying to exec 'cc1': execvp: No such file or directory
I gave full permission (0777) to test.php,
$ whereis cc1 // cc1:
Please find below version I am using
gcc version 5.4.0
PHP 7.0.32
OS: ubuntu 16.04
server : Nginx
Is there any alternate to run C and C++ using PHP or how to resolve this issue whille running from the browser.

Answer 1

Reading the error message, the problem comes from two issues:
php cannot find gcc since $path variable is not correctly set, in php file, you should type something like PATH=/usr/bin && gcc /var/www/test/main.c. In this example, gcc and other stuff are in /usr/bin directory. To know where are located cc1 for instance, type find / -name cc1 and add it to $PATH: PATH=/some/path:/some/other/path
Current directory of php could no be writtable, so indicate where the generated file must be created: gcc /var/www/test/main.c -o /var/www/test/main
Directory /var/www/test must be writable by user running php program.
Note that the user running the php program is not necessary the root...
So your php file should looks like:
<?php
$output = shell_exec("PATH=/usr/bin && gcc /var/www/test/main.c -o/var/www/test/main 2>&1");
print_R($output);
?>