I am developing an online testing system through which we can conduct online programming contests.
For the same i want to invoke the C compiler from the php script using the functions like system(), shell_exec(), exec() etc. But the function is not creating a.out file
when i wrote g++ a.cpp -o a using terminal it worked.
But this is not working
system("g++ a.cpp -o a",$as); //a.cpp is inside www folder
PHP runs as a different user to yourself, and so probably doesn't have permission to execute the g++ command.
To make the command accessible to PHP, try this:
sudo chmod o+x /usr/bin/g++
N.B. /usr/bin/g++ can sometimes be a symbolic link to another executable in the same directory, and so changing its permissions won't do anything (symlinks are 777 by default). If the above command doesn't resolve the issue, can you add the output of this command to your question, which will show where it points to:
ls -al /usr/bin/g++
On my system, this outputs
lrwxrwxrwx 1 root root 7 2011-08-10 14:52 /usr/bin/g++ -> g++-4.5
This means g++ is essentially an alias of g++-4.5, so I would allow 'other' execute permissions on g++-4.5 instead:
sudo chmod o+x /usr/bin/g++-4.5
sudo chmod o+x /usr/bin/g++-4.6. I've added a more generic solution to my question.system('g++ /var/www/a.cpp -o /tmp/a.out', $as);. If that works, you can then go on to change the output location - but make sure 'other' has write access to the directory.