Real Time Output Issue resolved: I did encountered similar issue in Python, while capturing the real time output from c program. I added " fflush(stdout) ;" in my C code. It worked for me. Here is the snip the code << C Program >> #include <stdio.h> void main () { int count = 1 ; while ( 1 ) { printf ( " Count %d\n" , count ++); fflush ( stdout ); sleep ( 1 ); } } << Python Program >> #!/usr/bin/python import os , sys import subprocess procExe = subprocess . Popen ( ".//count" , shell = True , stdout = subprocess . PIPE , stderr = subprocess . PIPE , universal_newlines = True ) while procExe . poll () is None : line = procExe . stdout . readline () print ( "Print:" + line ) << OUTPUT>> Print: Count 1 Print: Count 2 Print: Count 3 UPDATE:: The above one has flaws as we are reading only oneline per poll iteratio