Re: Sort with header/skip-lines support (original) (raw)

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From: Assaf Gordon
Subject: Re: Sort with header/skip-lines support
Date: Fri, 11 Jan 2013 14:19:10 -0500
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.4) Gecko/20120510 Icedove/10.0.4

Hello Pádraig,

Your suggestions work for all the cases I needed, so essentially there's already a way to do sort+header - much appreciated!

Pádraig Brady wrote, On 01/11/2013 01:13 PM:

On 01/11/2013 04:10 PM, Assaf Gordon wrote: > Pádraig Brady wrote, On 01/10/2013 07:11 PM: > > The following indeed works with sed 4.2.2 ( on linux 3.2 ): > $ ( echo 99 ; seq 10 ) | ( sed -u 1q ; sort -n ) > > [2] - no pipe support: > http://lists.gnu.org/archive/html/bug-coreutils/2007-07/msg00215.html > But I'm wondering (as per the link above [2]) if this is posix compliant and > stable (i.e. can this be trusted to work everytime, even on non-linux > machines?).

No sed -u with this functionality is not portable. Though it's more portable than sort --header given that it already exists :)

Sorry for nitpicking, but just to verify: "sed -u" is a GNU extension, hence not portable by definition. But what I meant to ask: If I install GNU sed + GNU sort on any machine (e.g. MAC OSX), would it work in a reliable way? Eric Blake's email seemed to suggest this will never be guaranteed to work (even if it works in practice) due to sharing pipes between processes.

For completeness, showing the current options for such cases...

Thanks for taking the time to write these - very helpful.

-gordon