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

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?

does the python command work when typed directly into the command line? — Jeemusu
– Jeemusu, Commented Mar 5, 2013 at 6:36
@Jeemusu It does, and it also works when I execute the command above from a simple test.php file. — cybertextron
– cybertextron, Commented Mar 5, 2013 at 17:06
Are the test.php and codeigniter code being run on the same server? — Jeemusu
– Jeemusu, Commented Mar 7, 2013 at 7:11
what does python -c "print(1); exit(10)" and env python --version do? — User
– User, Commented Mar 10, 2013 at 10:31

Community · Accepted Answer · 2017-05-23 11:59:43Z

4

+25

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!

edited May 23, 2017 at 11:59

CommunityBot

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answered Mar 16, 2013 at 5:58

Kautil

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Comments

Cyril · Accepted Answer · 2013-03-16 05:43:59Z

1

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.

answered Mar 16, 2013 at 5:43

Cyril

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Comments

Matt Ellen · Accepted Answer · 2013-03-05 12:10:35Z

0

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);

edited Mar 5, 2013 at 12:10

Matt Ellen

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answered Mar 5, 2013 at 12:08

Youn Elan

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1 Comment

cybertextron Over a year ago

a couple of things: I created a mock test.php file, and I executed the program, and it worked as supposed. Then when I executed my script.py the results were the expected. The problem appears to be when I try to execute it from codeigniter.

Peinguin · Accepted Answer · 2013-03-05 15:24:54Z

0

system returns only last line. system

public function deploy_test() {

      system("python --version", $out);
      echo json_encode(implode($out));
 }

answered Mar 5, 2013 at 15:24

Peinguin

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2 Comments

cybertextron Over a year ago

it returns 0 only. and $out needs to be an array in order to work with implode ( it is not ).

Peinguin Over a year ago

Sorry. Python -v returns output into second stream. You have to use $retval = exec("/usr/bin/python --version 2>&1", $out); var_dump($retval);

unicorn80 · Accepted Answer · 2013-03-15 10:47:13Z

0

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;

answered Mar 15, 2013 at 10:47

unicorn80

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