Dot Dot (..) in Filesystems – Behavior with Symlinks Explained

I think the thing to do is have your php/python return the data directly instead of apache. Your code can do the same thing that apache does. In my experience this is much better than opening up another directory and/or using sudo, or changing file permissions for apache, etc.

If the program produces the large file faster than the internet connection, then you can stream the data directly from your program, which eliminates the extra data file and the code to manage it and the mechanisms to remember it.

This answer on Stack Overflow shows how the code works in php. https://stackoverflow.com/a/4357904/5484716.

For programs that will be called this way, eliminate all stderr stream output and make sure the return code from your python process accurately reflects the success or failure of the process.

The examples below show the popen() calls you would use in the above example scenario from stackoverflow. I've prepended exec 2>/dev/null; to the shell command. This ensures that no output goes to stdandard error, even from the shell itself, because having data coming on both stderr and stdout can be a source of deadlocks with popen().

If you want to download the disk file to your user:

$fp = popen('exec 2>/dev/null; sudo -u theuser cat yourfile.zip', 'r');

If you want to download the data from the active process:

$fp = popen('exec 2>/dev/null; sudo yourpythonscript arg argN', 'r');

These command lines are shell commands and need to be quoted appropriately for shell meta characters.

In the second method, the server would begin sending the data immediately. When the user successfully submits the form, they immediately see a "save as" dialog from their browser. As soon as the user selects the output file, your php script transmits the data directly across the wire and into the remote file.

The python script should print only the zip data on standard output, and return an exit code that accurately represents the success or failure of the zip process. In python the script should write the output on sys.stdout, for example zf = ZipFile(sys.stdout, ....

It is critical to call pclose() and check the return value, because that will be the only way you know if the zip succeeded or not. If pclose() returns anything other than 0, something is wrong.

How the file is handled by the client depends on the settings of these response headers and others: content-type:, content-encoding:, and content-disposition: See: http://www.w3.org/Protocols/rfc2616/rfc2616-sec6.html, look at the response-header and the entity-header information.