Topic: CGI setup

[Tycek]

Hello.
I have been trying to setup my Apache server so it can run CGI scripts. I run this script in python and it is really simple script, which should output just "Hello CGI" to the site.
When I try to access this script from browser, it gives me Internal server error and in the error log there is a message, that says "End of script output before headers".
When I save that script as .py file, it runs just fine.
Also when I try to run the .cgi file in terminal on server, it works fine too.
I tried to change the apache2.conf file, where I added directory with the cgi-bin folder, but it still did not solve my problem.
I have this server on VPS, where runs Ubuntu 14.04 64-bit with PLESK installed on it.

Thank you for your replies.

[Steffen]

This is typically an error that occurs when you are unable to view or execute the file, try:

chmod 755 the_file

You can also try to add -w th=o the shebang


#!/usr/bin/perl -w

[Tycek]

I gave it 777 permission via PLESK, but it still does not work.

-w in the shebang also did not solve it.

[Jan-E]

A *.py file is being executed by python, a *.cgi usually by perl. Could you post the contents of the script? Does it need python?

[Tycek]

It needs python, since the project I want to publish, is written in python.

Content of CGI file:

[Jan-E]

Try https://www.linux.com/blog/configuring-apache2-run-python-scripts

I do not know if 'import cgitb' is required, but you might be able to test it.

Or, on Ubuntu 16.04 LTS:
https://www.server-world.info/en/note?os=Ubuntu_16.04&p=httpd&f=5

Not that both articles contain 'a2enmod cgi'.

[Tycek]

I tried to configure it according to those sites, but it still does not work.
Command a2enmod says, that CGI is enabled. Restarting Apache also did not solve it.

[mraddi]

Might help or not - here are the steps that I used to get this script to work on Ubuntu 16.04 - Python3 was already installed:

Installed Apache2 (sudo apt-get install apache2)
enabled cgi (sudo a2enmod cgi)
saved the script (without the "-w") into /var/www/cgi-bin/helloworld.py (vi /var/www/cgi-bin/helloworld.py)...
...and made it executable (chmod a+x /var/www/cgi-bin/helloworld.py)
edited apache2's config as cgi seems to use /usr/lib/cgi-bin as default instead of my /var/www/cgi-bin
restarted apache2 (sudo service apache2 restart)
http://192.168.0.4/cgi-cin/helloworld.py worked as well as http://192.168.0.4/cgi-bin/motd.pl (192.168.0.4 is my Ubuntu-"Server", both files [pl and py] are located in the same directory)

By the way - the interesting part in the /etc/apache2/conf-available/serve-cgi-bin.conf looks this way:

[James Blond]

Also make sure to have the Linux line endings. A file save on windows can cause some trouble.

[Tycek]

OK, so I decided not to execute it as .cgi file, but as .py file since that works.

But I stumbled on another problem. It seems that the CGI ignores the shebang line which says

[Jan-E]

Try renaming /usr/bin/python in /usr/bin/python2 and /usr/bin/python3 in /usr/bin/python.

Probably Apache looks for 'python' in the directories specified in the PATH variable. In my case the PATH variable contains

/sbin:/usr/sbin:/bin:/usr/bin

[Tycek]

So you say, that I should try to rename the link

/usr/bin/python3 to /usr/bin/python

so the apache takes the python3 instead of the default python?

This change should be reversible if something goes wrong right?
I still wonder why it ignores the shebang though.