php exec fails to launch browser via bash script

Question

On a Raspberry Pi 3B+ (using stretch), I have a bash script that looks like this.

pkill chromium-browse
chromium-browser --noerrdialogs --disable-infobars --kiosk https://www.example.com --incognito

The bash script works fine when it is run at the command prompt. I am executing it in php like this:

@exec("sudo bash /var/www/local.example.com/restartbrowser.sh", $output, $resultCode);

The script executes and the first line (pkill) executes. However, the second line does not. I get the following from $output:

[0]=> string(197) " --disable-quic --enable-tcp-fast-open --disable-gpu-compositing --ppapi-flash-path=/usr/lib/chromium-browser/libpepflashplayer.so --ppapi-flash-args=enable_stagevideo_auto=0 --ppapi-flash-version=" [1]=> string(151) "[3448:3448:0902/120435.075925:ERROR:zygote_host_impl_linux.cc(89)] Running as root without --no-sandbox is not supported. See https://crbug.com/638180."

and $resultCode is 1

I have also tried executing the script without the sudo and the $output is:

array(1) { [0]=> string(197) " --disable-quic --enable-tcp-fast-open --disable-gpu-compositing --ppapi-flash-path=/usr/lib/chromium-browser/libpepflashplayer.so --ppapi-flash-args=enable_stagevideo_auto=0 --ppapi-flash-version=" }

but no browser is launched.

Note that the line that starts the browser is exactly the same in my autostart file - i.e. ~/.config/lxsession/LXDE-pi/autostart and it works fine there.

I have also tried adding 2>&1 to the end of the command but that doesn't appear to do anything. The permissions on all files in that directory are:

-rwxr-x--- 1 pi www-data

What could be the problem? Any suggestions to troubleshoot and/or fix the problem will be greatly appreciated.

EDIT: I also tried the following line in the php file:

 @exec("su -c '/var/www/pb.podrones.com/restartbrowser.sh' pi", $output, $resultCode);

to no avail. :-(

CLARIFICATION

I neglected to mention the obvious - that I have the following to enable execution of programs by www-data (using sudo visudo to add the below line)

www-data        ALL=NOPASSWD: ALL

Answer 1

It seems that you're running your script as root. If that is the case, then the problem is clear: chromium will not run as root. You need to pick a different user for this task.

Next question is, does PHP have access to the X server? Running xauth list instead of the browser (and checking its output) will probably shed some light on the matter. This answer explains how to share X server cookies between users.