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Re: Other difference with Perl: Python scripts in a pipe

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From Peter Otten <__peter__@web.de>
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Subject Re: Other difference with Perl: Python scripts in a pipe
Date Thu, 10 Mar 2016 23:09:21 +0100
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Ian Kelly wrote:

> On Thu, Mar 10, 2016 at 2:33 PM, Fillmore <fillmore_remove@hotmail.com>
> wrote:
>>
>> when I put a Python script in pipe with other commands, it will refuse to
>> let go silently. Any way I can avoid this?
> 
> What is your script doing? I don't see this problem.
> 
> ikelly@queso:~ $ cat somescript.py
> import sys
> 
> for i in range(20):
>     sys.stdout.write('line %d\n' % i)
> ikelly@queso:~ $ python somescript.py | head -5
> line 0
> line 1
> line 2
> line 3
> line 4
> ikelly@queso:~ $ python3 somescript.py | head -5
> line 0
> line 1
> line 2
> line 3
> line 4

I suppose you need to fill the OS-level cache:

$ cat somescript.py 
import sys

for i in range(int(sys.argv[1])):
    sys.stdout.write('line %d\n' % i)
$ python somescript.py 20 | head -n5
line 0
line 1
line 2
line 3
line 4
$ python somescript.py 200 | head -n5
line 0
line 1
line 2
line 3
line 4
$ python somescript.py 2000 | head -n5
line 0
line 1
line 2
line 3
line 4
Traceback (most recent call last):
  File "somescript.py", line 4, in <module>
    sys.stdout.write('line %d\n' % i)
IOError: [Errno 32] Broken pipe

During my experiments I even got

close failed in file object destructor:
sys.excepthook is missing
lost sys.stderr

occasionally.

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Thread

Other difference with Perl: Python scripts in a pipe Fillmore <fillmore_remove@hotmail.com> - 2016-03-10 16:33 -0500
  Re: Other difference with Perl: Python scripts in a pipe Ian Kelly <ian.g.kelly@gmail.com> - 2016-03-10 14:46 -0700
    Re: Other difference with Perl: Python scripts in a pipe Fillmore <fillmore_remove@hotmail.com> - 2016-03-10 17:04 -0500
  Re: Other difference with Perl: Python scripts in a pipe Peter Otten <__peter__@web.de> - 2016-03-10 23:09 +0100
  Re: Other difference with Perl: Python scripts in a pipe Ian Kelly <ian.g.kelly@gmail.com> - 2016-03-10 15:16 -0700
    Re: Other difference with Perl: Python scripts in a pipe Fillmore <fillmore_remove@hotmail.com> - 2016-03-10 18:48 -0500
      Re: Other difference with Perl: Python scripts in a pipe INADA Naoki <songofacandy@gmail.com> - 2016-03-11 09:08 +0900
        Re: Other difference with Perl: Python scripts in a pipe Fillmore <fillmore_remove@hotmail.com> - 2016-03-10 19:26 -0500
          Re: Other difference with Perl: Python scripts in a pipe Alan Bawden <alan@csail.mit.edu> - 2016-03-11 01:45 -0500
            Re: Other difference with Perl: Python scripts in a pipe Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-03-11 12:15 +0200
          Re: Other difference with Perl: Python scripts in a pipe Ethan Furman <ethan@stoneleaf.us> - 2016-03-11 00:55 -0800

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