script won't execute certain commands

gistenjunge

Hi,

I have the following problem. I'm running an Apache web server with php module on a Linux box.
Sometimes php commands are ignored. My script is like this:

echo "line 1";
exec ("something");
echo "line 2";

The output of the echo lines is shown on the HTML page, but the execute command is ignored.
Even if I use 'non-existing commands' like

jhgkjghkj;

I don't get an error message.

A few weeks ago it worked. I don't remember exactly the changes I made, but I think I only installed SSL support (as a module, too).

What's wrong?
Thaks in advance for any help 🙂

Hoelz

Anon

I believe exec returns the result:

$cmd = exec("junk");

And system prints the results to STDOUT.

system("junk");

gistenjunge

Thanks for the quick reply,
but I don't want any output. I just want the command to be executed...

Hoelz

sepodati

How do you know if the command is being executed if you don't look at what's returned?

Also, are you sure you're not running in safe mode?

---John Holmes...

gistenjunge

I know because the exec command is supposed to start a daemon. As return value I get '1'.
And if I do a 'ps' on the console, I can see that the process is not running.

But why does a thing like
i_do_not_exist();
not result in an error message?

Hoelz

smarlowe

that's not the same. i_do_not_exist() is a function reference. exec("somecommand") is a system call to run an external command. Whether the command finishes or runs or not exec is still a legal built in function, so php doesn't complain. It's pretty much the job of the programmer to check the output code of an executed program to see if it ran or not.

If you are trying to start a daemon, it may be that it needs to be run as root to latch onto a port below 1024 or something. Have you tried launching the daemon from the command like as the httpd or nobody user (httpd usually runs as one or the other).

If that won't let it run, you may need to set the suexec bit on the executable with:
'chown root.httpd daemon'
'chmod 4750 daemon'
Then httpd can run the daemon as root.

Note that the above assumes that httpd runs as the httpd user in the httpd group, and that the daemon you wanna launch is called daemon.

Oh, and you may need to redirect input and output so that the daemon can properly detach from the launching environment of php. Some daemons need this, most don't.

gistenjunge

thanks!

this might help.

hoelz