How do I make the code which execute the python file (not itself) with input redirection?

Question

I want to make call.py which execute main.py with input redirection of input.txt.

In addition to that,I don't want to change the code of main.py.

What I want to do is like below.

call.py

exec(open("./main.py").read() < input.txt)

Of course I know that this code doesn't work.

main.py

name=input()
x=int(input())
print(name +" has chosen "+str(x)+".")

input.txt

Alice
2

Please give me the advice for it.

Answer 1

You can use the subprocess module for this. A sample usage is shown below.

In call.py:

proc = subprocess.Popen( "main.py input.txt", stdout = subprocess.PIPE, stderr = subprocess.PIPE )

All you have to do in main.py is read the contents of input.txt by using the sys module. To fetch input.txt from the command line, use sys.argv[1].

Answer 2

Just writing this is enough:

os.system('main.py < input.txt')