[Tutor] Simple question on creating a filter
Smith, Jeff
jsmith at medplus.com
Fri Feb 11 16:26:50 CET 2005
Good catch Bill,
I was using assoc and ftype to allow me to run my filter.py directly as
a command and using:
filter < file
Unfortunately, Windows doesn't handle this properly and I had to do
C:\Python24\python filter.py < file
To get it to work.
Thanks,
Jeff
P.S. In retrospect, I've had the same problem with Perl but because of
my newbie status I assumed I was doin' something wrong :-)
-----Original Message-----
From: Bill Mill [mailto:bill.mill at gmail.com]
Sent: Friday, February 11, 2005 9:38 AM
To: Smith, Jeff
Cc: tutor at python.org
Subject: Re: [Tutor] Simple question on creating a filter
On Fri, 11 Feb 2005 09:28:35 -0500, Smith, Jeff <jsmith at medplus.com>
wrote:
> I'm sorry to both with such a simple question but I've looked in the
> normal places and don't see the quick and dirty answer I know must
> exist.
>
No worries; that's what this list is for.
> I want to write a simple line selection filter that could be used
> like:
>
> filter < file
>
> In Perl I would do:
>
> while (<>)
> {
> print if line meets selection criteria;
> }
>
> I've tried what I thought would be the Python equivalent but it
> doesn't
> work:
>
> for line in sys.stdin:
> if line meets selection criteria:
> print line
>
> I get the following at runtime:
>
> Traceback (most recent call last):
> File "U:\TimeKeeper\mine.py", line 2, in ?
> for line in sys.stdin:
> IOError: [Errno 9] Bad file descriptor
>
I'm not quite sure how you're getting that "bad file dscriptor" error.
My code, also on windows (and cygwin) with python2.4:
/d/code/python$ cat test.py
import sys
for line in sys.stdin:
if line.startswith('a'):
print line.strip()
/d/code/python$ cat test_in
aline1
bline2
aline3
cline4
/d/code/python$ python test.py < test_in
aline1
aline3
Try to run it like I did, and let me know if it gives you the same
thing; that'll give us a common point of reference.
Peace
Bll Mill
bill.mill at gmail.com
> This is with Python 2.4 on Windows.
>
> Jeff
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