Re: Recommended way to truncate a shell variable value in autoconf

[Eric Blake]

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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