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Re: Recommended way to truncate a shell variable value in autoconf
From: |
Eric Blake |
Subject: |
Re: Recommended way to truncate a shell variable value in autoconf |
Date: |
Fri, 21 Feb 2014 17:09:28 -0700 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.3.0 |
On 02/21/2014 05:05 PM, Dale Visser wrote:
>> Date: Fri, 21 Feb 2014 16:57:28 -0700
>> From: address@hidden
>> To: address@hidden; address@hidden
>> Subject: Re: Recommended way to truncate a shell variable value in autoconf
>>
>> 'string : regexp' is portable. 'match string regexp' is not. For
>> example this use of expr is already present in pretty much any configure
>> file generated by modern autoconf:
>>
>> as_echo_body='eval expr "X$1" : "X\\(.*\\)"'
>
> Good. I think I have settled on this, but will go back to the expr solution
> if you think that would be better:
>
> X=`echo "$X" | sed 's/ .*// ' | sed 's/,.*//'`
sed|sed is a waste of a fork. Just go with:
X=`echo "$X" | sed 's/[, ].*//'`
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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