EOFError when starting with subproccess

Question

When i start my python3 script with subproccess from an other script i get the following error:

Select the keyword preset you want to use:Traceback (most recent call last):
  File "test2.py", line 9, in <module>
    keywordselect=input("Select the keyword preset you want to use:")
EOFError

But when i start the script normally with python3 generate.py it works totally fine with no error.

script1:

import subprocess
p = subprocess.Popen(["python3", "test2.py"])

script2:

print("Keyword")
print("1. Preset1")
print("2. Preset2")
print("3. Preset3")
print("4. Preset4")
print("You can edit the presets in /presets/keywords/.")
selecting = 1
while selecting == 1:
    keywordselect=input("Select the keyword preset you want to use:")
    if keywordselect == "1":
        print("You selected keyword preset 1.")
        selectedkeywordlist = "presets/keywords/preset1.txt"
    elif keywordselect == "2":
        print("You selected keyword preset 2.")
        selectedkeywordlist = "presets/keywords/preset2.txt"
    elif keywordselect == "3":
        print("You selected keyword preset 3.")
        selectedkeywordlist = "presets/keywords/preset3.txt"
    elif keywordselect == "4":
        print("You selected keyword preset 4.")
        selectedkeywordlist = "presets/keywords/preset4.txt"
    else:
        print("You didn't select a valid option, please try again.")

can you try `p = subprocess.call(["python3", generatefile])` ? you should show a [mcve] of your script1. — Jean-François Fabre, Aug 20 '18 at 10:19
Your second script expects to read from `stdin` on `input("Select the keyword preset you want to use:")` But you are not providing any for the invoked subprocess as far as I can see — FlyingTeller, Aug 20 '18 at 10:23
@Jean-FrançoisFabre python3 pre-generate.py File "generate.py", line 272 ^ SyntaxError: unexpected EOF while parsing — Thiplol, Aug 20 '18 at 10:27
@FlyingTeller i want the user to type 1 2 3 or 4 in the subproccess — Thiplol, Aug 20 '18 at 10:29
you probably redirected stdin earlier. Show a [mcve] of the first script — Jean-François Fabre, Aug 20 '18 at 10:32
@Jean-FrançoisFabre just the code above reproduces the problem for me `import subprocess p = subprocess.Popen(["python3", "generate.py"])` — Thiplol, Aug 20 '18 at 10:42
please [edit] your question to reflect that. Because it seems very hard to reproduce this issue — Jean-François Fabre, Aug 20 '18 at 10:47
@Jean-FrançoisFabre i edited it with exactly what i run and "Minimal, Complete, and Verifiable example " — Thiplol, Aug 20 '18 at 10:51

argo · Accepted Answer · 2018-08-20T11:12:47.777

2

You are using subprocess.Popen which is a by default non blocking, piece of code, hence You program cursor moves rather than waiting for the input from the user. But what you need is a code which is blocking your program cursor. subprocess.call exactly does it. It would be waiting for the other command to execute completely.

You need to use subprocess.call to solve your problem. Just change your script2 file with this

import subprocess
p = subprocess.call(["python", "abca.py"])

You can read more about the difference between subprocess.Popen and subprocess.call in this answer. Which describes when to use which command and the difference between them

edited Aug 20 '18 at 11:12

answered Aug 20 '18 at 11:03

argo

5,225
4
24
43

my first comment suggested that, and OP commented back that it had the same effect. – Jean-François Fabre Aug 20 '18 at 12:25
I could replicate the issue. And when I used `subprocess.call` it got solved – argo Aug 20 '18 at 12:27
Hahaha. Seems like you did the same mistake as I did. You were trying to execute it from IDE. Now while executing it from terminal it got replicated. :P – argo Aug 20 '18 at 12:31
Hahaha my mistake was trying to execute it in my head. Actually I thought that there was more than this in op first script. Let's see if you get acceptance. – Jean-François Fabre Aug 20 '18 at 12:35
the actual explanation is: the first script exits while the other script is running, breaking the input pipe. – Jean-François Fabre Aug 20 '18 at 12:36
Yes that would be the right explanation. I was not able to find the appropriate words. Why don't you edit the answer and put the right words? – argo Aug 20 '18 at 12:38

score 0 · Answer 2 · answered Aug 20 '18 at 10:59

0

You have to redirect stdin and stdout with the call of script2.py, can use subporcess.PIPE for that:

p = subprocess.Popen(["python3", "test2.py"], stdin=subprocess.PIPE, 
                     stdout=subprocess.PIPE)

answered Aug 20 '18 at 10:59

Andriy Ivaneyko

18,421
4
52
73

EOFError when starting with subproccess

2 Answers2