how to write bytes to stdout in python3.3

Question

A test file named == a.py ==

import os

if __name__ == '__main__':
    for x in range(0,1000):
        try:
            os.sys.stdout.buffer.write(b"hello\r\n")
            os.sys.stdout.buffer.flush()
        except OSError:
            pass

It is ok when it runs alone. But there is problem in following case:

1. Run python a.py | more
2. Press ctrl+c to exit

Then I got Exception OSError: OSError(22, 'Invalid argument') in <_io.TextIOWrapper name='' mode='w' encoding='cp936'> ignored

I have catch the OSError already around the os.sys.stdout.buffer operations, but it still goes wrong.

If i don't use os.sys.stdout.buffer.flush, then there's no error message. If I just use print(), everything is OK.

So how to write bytes to the stdout correctly?

I am using Windows 7 64 bit and Python 3.3.0 32 bit.

Answer 1

You can use os.fdopen to reopen stdout with different mode. You can get the file number for stdout with sys.stdout.fileno().

Example:

>>> fp = os.fdopen(sys.stdout.fileno(), 'wb')
>>> fp.write(b'Hello, world')
12
>>> sys.stdout.mode
'w'
>>> fp.mode
'wb'
>>> fp.flush()
Hello, world>>>