Running Python Scripts in C via Exec?

Question

I want to run a python script in C in the following manner: (I already forked)

err = execlp("python", "my_script.py", "test", (char*) NULL);

In bash, I can successfully run

python my_script.py test

(test is an argument for the python script)

However, the program outputs

my_script.py: can't open file 'test': [Errno 2] No such file or directory

What am I doing wrong? :3

Yes. It is trying to open 'test' but I never told it to. It should be passing test as an argument. — Reed B
– Reed B, Commented Jan 26, 2014 at 18:12
Can you verify that the current directory is the same I.e by setting it from within C? — SevenBits
– SevenBits, Commented Jan 26, 2014 at 18:13
Also, try hard coding the path to Python to verify that Python will run correctly when run in this manner. — SevenBits
– SevenBits, Commented Jan 26, 2014 at 18:14

Reed B · Accepted Answer · 2014-01-26 18:30:23Z

6

Ah, I figured it out. It should be:

execlp("python", "python", "my_script.py", "test", (char*) NULL);

The first argument, by convention, is the filename of the executable. I thought that this was automatically passed but apparently it is not.

answered Jan 26, 2014 at 18:30

Reed B

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2 Comments

Just FYI, there is no need ever to cast NULL, at least in C. I assume the same is true for C++, but I'm not totally sure.

or one can use system("python my_script.py arg1, arg2").