Streaming pipes in Python -

i'm trying convert output of vmstat csv file using python, use convert csv , add date , time coloumns:

vmstat 5 | python myscript.py >> vmstat.log 

the problem i'm having blocks while trying iterate sys.stdin. seems input buffer doesn't flushed. don't want endlessly loop around , burn processor time i'm trying measure this. here's simple demonstration blocks on line 3:

import sys  line in sys.stdin:     sys.stdout.write(line)     sys.stdout.flush() 

is there easy way access stream grep does, without pausing while input buffer fills up?

vmstat 5,does not close stdout, python buffer still waiting more data.

use instead:

for line in iter(sys.stdin.readline, ""):     print line