How to pipe input to python line by line from linux program?

Instead of using command line arguments I suggest reading from standard input (stdin). Python has a simple idiom for iterating over lines at stdin:

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

My usage example (with above's code saved to iterate-stdin.py):

$ echo -e "first line\nsecond line" | python iterate-stdin.py first linesecond line

With your example:

$ echo "days go by and still" | python iterate-stdin.pydays go by and still

What you want is popen, which makes it possible to directly read the output of a command like you would read a file:

import oswith os.popen('ps -ef') as pse:    for line in pse:        print line        # presumably parse line now

Note that, if you want more complex parsing, you'll have to dig into the documentation of subprocess.Popen.

I know this is really out-of-date, but you could try

#! /usr/bin/pythonimport sysprint(sys.argv, len(sys.argv))if len(sys.argv) == 1:    message = input()else:    message = sys.argv[1:len(sys.argv)]print('Message:', message)

and I tested it thus:

$ ./test.py['./test.py'] 1this is a testMessage: this is a test$ ./test.py this is a test['./test.py', 'this', 'is', 'a', 'test'] 5Message: ['this', 'is', 'a', 'test']$ ./test.py "this is a test"['./test.py', 'this is a test'] 2Message: ['this is a test']$ ./test.py 'this is a test'['./test.py', 'this is a test'] 2Message: ['this is a test']$ echo "This is a test" | ./test.py['./test.py'] 1Message: This is a test

Or, if you wanted the message to be one string, each and every time, then

    message = ' '.join(sys.argv[1:len(sys.argv)])

would do the trick on line 8