popen communicate in Python

0 votes

1st.py creates a REPL (read-eval-print-loop):

print "Something to print"
while True:
    r = raw_input()
    if r == 'n':
        print "exiting"
        break
    else:
        print "continuing"

I then launched 1st.py with the following code:

p = subprocess.Popen(["python","1st.py"], stdin=PIPE, stdout=PIPE)

And then tried this:

print p.communicate()[0]

It failed, providing this traceback:

Traceback (most recent call last):
  File "1st.py", line 3, in <module>
    r = raw_input()
EOFError: EOF when reading a line

Can you explain what is happening here please? When I use p.stdout.read(), it hangs forever.

Nov 13, 2018 in Python by findingbugs
• 3,260 points
2,745 views

1 answer to this question.

0 votes
Your second bit of code starts the first bit of code as a subprocess with piped input and output. It then closes its input and tries to read its output.

The first bit of code tries to read from standard input, but the process that started it closed its standard input, so it immediately reaches an end-of-file, which Python turns into an exception.
answered Nov 13, 2018 by Priyaj
• 58,090 points

Related Questions In Python

+3 votes
7 answers

How can I rename a file in Python?

yes, you can use "os.rename" for that. ...READ MORE

answered Mar 31, 2018 in Python by DareDev
• 6,890 points
19,318 views
+2 votes
2 answers

How can I create a new file in Python?

You can try the below code which ...READ MORE

answered Mar 31, 2018 in Python by anto.trigg4
• 3,440 points
958 views
+2 votes
3 answers

what is the practical use of polymorphism in Python?

Polymorphism is the ability to present the ...READ MORE

answered Mar 31, 2018 in Python by anto.trigg4
• 3,440 points
4,245 views
+2 votes
2 answers

Error while printing hello world in python.

You must be trying this command in ...READ MORE

answered Mar 31, 2018 in Python by GandalfDwhite
• 1,320 points
5,246 views
0 votes
2 answers
+1 vote
2 answers

how can i count the items in a list?

Syntax :            list. count(value) Code: colors = ['red', 'green', ...READ MORE

answered Jul 7, 2019 in Python by Neha
• 330 points

edited Jul 8, 2019 by Kalgi 4,023 views
0 votes
1 answer
+2 votes
3 answers

How can I play an audio file in the background using Python?

down voteacceptedFor windows: you could use  winsound.SND_ASYNC to play them ...READ MORE

answered Apr 4, 2018 in Python by charlie_brown
• 7,720 points
12,875 views
+1 vote
1 answer

How to create plots using python matplotlib in IPython notebook?

I think you should try: I used %matplotlib inline in ...READ MORE

answered Aug 8, 2018 in Python by Priyaj
• 58,090 points
1,189 views
webinar REGISTER FOR FREE WEBINAR X
REGISTER NOW
webinar_success Thank you for registering Join Edureka Meetup community for 100+ Free Webinars each month JOIN MEETUP GROUP