executing python in the command line inside a controller - PHP/CodeIgniter - php

Question

Inside my automation.php controller, I have the following function:
public function deploy_test() {
echo json_encode(system("python --version"));
}
When the user wants to deploy a test, by clicking a test button in the webpage, he would be able to accomplish such a task.
However, when I click the test button, my output is:
""
Meanwhile, when I execute the same function with the command:
public function deploy_test() {
echo json_encode(system("ls -l"));
}
I'm getting:
total 32
drwxr-xr-x. 15 philippe philippe 4096 Mar 4 16:48 application
drwxrwxr-x. 2 philippe philippe 4096 Mar 4 17:28 css
-rw-r--r--. 1 philippe philippe 6357 Jan 30 11:53 index.php
drwxrwxr-x. 2 philippe philippe 4096 Feb 27 15:38 js
-rw-r--r--. 1 philippe philippe 2496 Jan 30 11:53 license.txt
drwxr-xr-x. 8 philippe philippe 4096 Jan 30 11:53 system
drwxr-xr-x. 12 philippe philippe 4096 Jan 30 11:53 user_guide
Could someone please help me to get that straighten out?

Answer 1

The problem is not with your code or PHP.
The problem is with your permissions.
php uses permissions which are set in the env-vars of apache.
Which is ideally set as :
User ${APACHE_RUN_USER}
Group ${APACHE_RUN_GROUP}
under your apache2 / httpd conf file.
For example:
Try running:
<?= `whoami` ?>
via your shell and via your browser.
Your browser will probably say www-data and shell will say your username or if you are on AWS - default, you would get root
You do not have to use system() , use exec() instead.
We should be close as :
echo json_encode(exec("python --version"));
Performing operations will require you to have correct User and Groups set.
Look up for : In the shell, what does " 2>&1 " mean?
So your code should be :
echo json_encode(exec("python --version 2>&1"));
Hope it helps!

Answer 2

This works fine for my production server
public function deploy_test() {
echo json_encode(system("python --version 2>&1"));
}
with the output
Python 2.7.3
"Python 2.7.3"
Output of the unix command printed twice as system() itself outputs the result to browser. So exec() can be used in the place of system to avoid this.
public function deploy_test() {
echo json_encode(exec("python --version 2>&1"));
}
which outputs
"Python 2.7.3"
as expected.

Answer 3

I suspect it is not in the path. Try:
Type the full path to the python command (such as /usr/bin/python --version)
Find out with the command which, 'which python'
try executing your script from the command line, 'php script.php' => sometimes the web
server sets up things differently
make sure the error displaying is enabled with
ini_set('display_errors',1);

Answer 4

system returns only last line.
system
public function deploy_test() {
system("python --version", $out);
echo json_encode(implode($out));
}

Answer 5

It's a bit of hack, but you can find out the version number with 1 decimal even if you aren't allowed to execute python (which is the case with the 'user' CI).
//find python path
exec("which python", $path);
//show all subdirs in python
exec("ls -l ".$path[0]."*", $output);
$output = implode("\n", $output);
//preg match on version numbers
preg_match_all("#python(\d+(?:\.\d{1,2})?)#", $output , $matches);
$installed_versions = $matches[1];
//sort in reversing order
$versions_sorted_desc = array_reverse($installed_versions);
//latest version is element 0
$latest_version = $versions_sorted_desc[0];
echo $latest_version;