trouble with wrapping a c program

Sanne Korzec sanne at
Fri Jul 24 08:34:53 EDT 2009

Hi Mailing,


I am using a c program, which first initializes for some seconds and then
waits for user input (keyboard) to type something. When enter is pressed the
c program continues. 


I have wrapped this program in a python script, which starts the c program.
To start the c program, there are many options in python e.g.


Os.system os.popen or subprocess.popen 

To me there does not seem to be a difference for starting the program. They
all work well.


However the problem occurs when I want to input data during this c program. 


Using the keyboard and then enter in the c program prompt works, but I wish
to do this from the python script by sending the string from the python


I am able to print the string from python with a print command or with a
stdout.write command. But this simply prints it to the prompt, the c program
does nothing with this printed string.


Is there a way to pipe, stream, or send this string to the running c


All tutorials about piping I have read, seem to have to wait for the process
to finish. Or need the stdin string before starting the program.

Note that the c program is not finished when the input is needed, so I
cannot use or wait.

It is possible to give the user input in advance, but I do not want this,
because this makes everything much slower!

I really would like to do this during/while the c program is running.


I have created a thread and a small xmlrpc server for this and this works
fine. However I cannot seem to pass the string.


Here is a small fragment of my code:



cmd = [a list of my program and arguments]

subprocess.Popen(cmd)   #starts the c program



#somewhere along the way



#Sys.stdin = str

            #subprocess.stdin = str



I have spent the entire night trying to get this to work, but I can't seem
to get it right. Any help is much appreciated. Also, if anybody could
explain me where the fuck-up in my brain is, I would be very happy..




-------------- next part --------------
An HTML attachment was scrubbed...
URL: <>

More information about the Python-list mailing list