python import fails when called from PHP

Question

I'm having a puzzling problem when trying to import a module in python only when the script is called from php via system or exec.

From the python shell:

import igraph #This works.

if the previous line was in a file, say, test_module.py, then:
python test_module.py in the bash works.

Within PHP:
exec("python test_module.py",$output,$retval) -> fails : $retval = 1.

However, if the script is instead : import math, then this is fine.

Anybody ever dealt with something similar?

Answer 1

Is the igraph module in Python's standard module path, or is it in the same directory as your individual script? If so, it's quite possible that PHP is calling the python file with a different working directory, and it's trying to import things relative to that path instead of the path of the script.

Answer 2

one thing to check is sys.path

see what the difference is when called each way