Help with a regular expression???
crp at cmc.net
Wed Jan 27 17:04:12 UTC 2010
Amedee Van Gasse (ub) wrote:
> On Wed, January 27, 2010 15:06, Kevin O'Gorman wrote:
>> However that may be, I would suggest a perl filter, which is a one-liner
>> suitable for a pipeline.
>> perl -p -e 's/ ([^ ])/_ \1/g;'
>> -p: copy everything in a loop
>> -e: statement for the loop follows
>> s/ / /g: do a substitution on everything (g=multiple times on a
>> ( ): remember this
>> [^ ]: a character class consisting of any one non-space character.
>> Probably does not match newlines either.
>> \1 : the first remembered thing
>> Hope this helps.
> The same regex syntax can be used with the bash command sed:
> sed 's/ ([^ ])/_ \1/g'
> This *may* be a bit faster than using heavyweight perl. OTOH perl can do a
> lot more than sed, so it depends on what you want to do.
Ok, here is what I just tried -
DescriptionSection=" - Multidimensional Array Objects
* Efficient arrays of homogeneous machine types (floats, longs,
_ complex doubles)
* Arbitrary number of dimensions
* Sophisticated structural operations
- Universal Function Objects
* Support mathematical functions on all Python objects
* Very efficient for array objects"
DescriptionSection=`echo | sed 's/ ([^ ])/_ \1/g'`
And I get the following cryptic error, which tells me nothing. Can you help?
sed: -e expression #1, char 19: invalid reference \1 on `s' command's RHS
Thanks, Ray Parrish
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