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I have a python script which is needed to be run by php:

     <?php
     $command = escapeshellcmd('/home/Desktop/test.py');
     $output = shell_exec($command);
     echo $output;

     ?>

The out put of the python script is a binary file but I get the following error in the log: Unable to access the X Display, is $DISPLAY set properly?

The php code works fine from the terminal but no luck when I try to run it from the browser. Any idea what is going on? Ideally, I don't want to change my program. I want to know how you can rectify the X Display error. Is there a way to check if $DISPLAY is set properly? ( I am working with Ubuntu)

I tried this : pidof X && echo "yup X server is running" on my terminal and it is saying yup x server is running!

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  • 1
    Sounds like $DISPLAY isn't set. Why are you trying to run a GUI app from a webserver? Commented Apr 28, 2015 at 19:20
  • echo prints out strings, si shell_exec should return a string. I think that you have to modify your python script to return only string and it should not use any GUI. Commented Apr 29, 2015 at 17:41
  • Your app uses something that uses the X server. The terminal user probably has the X server running, so it works. The PHP running user does not have the X server running, so it doesn't work. My suggestion would be to modify the script to not use any X requiring methods or start X and access it somehow. Commented Apr 29, 2015 at 18:30

3 Answers 3

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Add the following text as the first line of your Python script:

#!/usr/bin/python

Without this, the kernel doesn't know what interpreter to run your script with, and may end up trying to launch it using /usr/bin/import (because that word probably appears on the first line of the script). The import utility requires access to the X11 display (it's a screenshot utility, basically), which is why you're getting this error.

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5 Comments

What about if the server is Windows?
@sємsєм If they're using something like Cygwin, it'll work! If not, we'd need to know a lot more about their configuration.
This is my first line of python script: #!/usr/bin/env python so should I change it to #!/usr/bin/python ?
Hmm, no, that should be fine then. Can you answer some of the comments on your post asking what your script is doing?
The output is saved in a C++ format ....self.blocks_file_meta_sink_0 = blocks.file_meta_sink( blocks.GR_FILE_FLOAT, True, int(header_every*250), self.extras_str, True)..It reads the data from another device
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The python file you need may need to open a window to run. You say you saw it run in terminal though? What's test.py? Is it propitiatory? If you try using this as a command in your PHP: (not 100% that the shell escape won't strip this so may need to comment that out)

python -c \'print \"Test\"\'

and see if you get the output text back. If so it's a python issue not PHP and the test.py file may be instantiating something that needs the $DISPLAY var set. PHP doesn't set the $DISPLAY var as it is shell commands not GUI.

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Sorry I don't understand what you mean by asking "Is it propitiatory?"..the program reads the data from a receiver.
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try popen

$command = "/usr/bin/python /home/Desktop/test.py";
$handle = popen($command, "r");

"r" for read

$read = fread($handle, 10);

10 is the size of output you want to take,

echo $read ;

hope it helps,

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2 Comments

This won't solve the problem. (In fact, it won't work at all, because the path to python is missing a slash.)
sorry that was a typo mistake,

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