[ILUG] Re: Re: Re: sed question

[Marcus Furlong]

On Saturday 16 August 2008 06:44 in
<20080816054430.A3912477C3 at blf.utvinternet.co.uk>, Brian Foster wrote:

>   | From: Marcus Furlong <furlongm at hotmail.com>
>   | Date: Fri, 15 Aug 2008 23:22:32 +0100
>   |[ ,.. ]
>   | Some of the tags contain an attribute, say "my_attribute",
>   | which according to the DTD, should only contain certain
>   | values. If the value is not valid, I want to remove the
>   | attribute entirely. E.g. if ASD SDF DFG FGH GHJ HJK are
>   | the valid values for this attribute, then the following:
>   | 
>   | <third my_attribute="ASD">
>   | <third my_attribute="AD AD">
>   | <third my_attribute="">
>   | <third my_attribute="HJK">
>   | 
>   | would become:
>   | 
>   | <third my_attribute="ASD">
>   | <third>
>   | <third>
>   | <third my_attribute="HJK">
>   | 
>   |[ ... ]  I'm sure there's a perl/sed one liner that could do it.
>   | Does anyone know how it could be done somewhat more elegantly?
> 
> sed -e '
> s/ my_attribute="ASD"/@="ASD"/g
> s/ my_attribute="SDF"/@="SDF"/g
> s/ my_attribute="DFG"/@="DFG"/g
> s/ my_attribute="FGH"/@="FGH"/g
> s/ my_attribute="GHJ"/@="GHJ"/g
> s/ my_attribute="HJK"/@="HJK"/g
> s/  *my_attribute="[^"]*"//g
> s/@="/ my_attribute="/g
> '
> 
>  rather common sed(1) trick.

Thanks Brian, works perfectly! :)

Could you explain what's happening in the above? I've searched for a similar
example with explanations but didn't find one, and now I'm all curious.

Marcus.