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bug#11631: closed (Re: bug#11631: Head command does not position file po
From: |
Eric Blake |
Subject: |
bug#11631: closed (Re: bug#11631: Head command does not position file pointer correctly for negative line count) |
Date: |
Thu, 07 Jun 2012 11:45:27 -0600 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:12.0) Gecko/20120430 Thunderbird/12.0.1 |
[please don't top-post on technical lists]
On 06/07/2012 08:37 AM, Anoop Sharma wrote:
> The thought behind the proposed change was that lseek should reflect
> the amount of data that head has actually been able to print.
But that's not generically possible to know.
>
> For example, how do we want head to behave in a situation like the
> following where files more than a particular size are not allowed
> (with bash shell on a machine with block size of 1024 bytes)? This
> situation can be handled by applying this patch. I agree this example
> is custom designed to illustrate my point but what do we gain by not
> making the check?:
>
> ulimit -f 1; trap '' SIGXFSZ
> (stdbuf -o0 head -n -1025 >someOutFile; cat) <someIpFile
>
> What should cat print now?
Bogus question. That's a bug in your shell scripting - if you are
worried about partial processing errors, then you must check all
intermediate steps:
ulimit -f 1; trap '' SIGXFSZ
(stdbuf -o0 head -n -1025 >someOutFile && cat) <someIpFile
That is, you should have used && rather than ;, so that cat prints
nothing on error.
--
Eric Blake address@hidden +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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- bug#11631: Head command does not position file pointer correctly for negative line count, (continued)
Message not available
- bug#11631: closed (Re: bug#11631: Head command does not position file pointer correctly for negative line count), Anoop Sharma, 2012/06/06
- bug#11631: closed (Re: bug#11631: Head command does not position file pointer correctly for negative line count), Jim Meyering, 2012/06/06
- bug#11631: closed (Re: bug#11631: Head command does not position file pointer correctly for negative line count), Eric Blake, 2012/06/06
- bug#11631: closed (Re: bug#11631: Head command does not position file pointer correctly for negative line count), Jim Meyering, 2012/06/06
- bug#11631: closed (Re: bug#11631: Head command does not position file pointer correctly for negative line count), Anoop Sharma, 2012/06/07
- bug#11631: closed (Re: bug#11631: Head command does not position file pointer correctly for negative line count), Jim Meyering, 2012/06/07
- bug#11631: closed (Re: bug#11631: Head command does not position file pointer correctly for negative line count), Anoop Sharma, 2012/06/08
bug#11631: closed (Re: bug#11631: Head command does not position file pointer correctly for negative line count),
Eric Blake <=
bug#11631: closed (Re: bug#11631: Head command does not position file pointer correctly for negative line count), Anoop Sharma, 2012/06/08
bug#11631: closed (Re: bug#11631: Head command does not position file pointer correctly for negative line count), Jim Meyering, 2012/06/06