You need two pieces: To read a line at a time in Python space and to emit a line at a time from Perl. The first can be accomplished with a loop like
while True:
result = pipe.stdout.readline()
if not result:
break
# do something with result
The readline
blocks until a line of text (or EOF
) is received from the attached process, then gives you the data it read. So long as each chunk of data is on its own line, that should work.
If you run this code without modifying the Perl script, however, you will not get any output for quite a while, possibly until the Perl script is finished executing. This is because Perl block-buffers output to a pipe by default. You can tell it to flush the buffer more often by changing a global variable in the scope in which you are printing:
use English qw(-no_match_vars);
local $OUTPUT_AUTOFLUSH = 1;
print ...;
See http://perl.plover.com/FAQs/Buffering.html and http://perldoc.perl.org/perlvar.html .