On 2/07/2006 5:02 AM, Christoph Haas wrote:
> Hi...
I encountered a problem that - according to my google search - other
people have found, too. Example code:
import sys
for line in sys.stdin:
print line
Running this code in Python 2.3 or 2.4 has the problem that I need to
send two EOFs (Ctrl-D) to break out of that loop.
Use case is a piped Python script that I run as a "CustomLog" pipe for
an Apache web server. I want to run all the log output through that pipe
but haven't had much luck. First it takes ages until the script
processes the input (even though I ran Python with "-u" to make it
unbuffered)
Which "it" did you expect to make unbuffered? -u unbuffers sys.stdout
and sys.stderr (and makes them binary, which wouldn't be a good idea on
a Windows box). If you are concerned that output shows up in real time,
use sys.stdXXX.flush().
> and then the script needs one EOF to do something with the
input and a second EOF to break out of the loop.
Is this a bug? I'm close to write a Perl script for this case. :(
I can reproduce your problem on Windows with Python 2.4.2 (note ^Z is
EOF for Windows):
|>> import sys
|>> for line in sys.stdin:
.... print >> sys.stderr, "->", repr(line)
....
line1
line2
line3
^Z
-> 'line1\n'
-> 'line2\n'
-> 'line3\n'
^Z
|>>
However this worked for me :
|>> import sys
|>> while 1:
.... line = sys.stdin.readline()
.... if not line: break
.... print >> sys.stderr, "->", repr(line)
....
line1
-> 'line1\n'
line2
-> 'line2\n'
^Z
|>>
The Library Reference Manual, section 2.3.9 (File Objects) says:
"""
Files support the iterator protocol. Each iteration returns the same
result as file.readline(), and iteration ends when the readline() method
returns an empty string.
"""
So yes, looks like a bug to me, but perhaps you don't need use Perl :-)
HTH,
John
