[ILUG] regular expression question

[Padraig Brady]

Mark McLoughlin wrote:

> Hi Padraig,
> 
> On Tue, 13 Nov 2001, Padraig Brady wrote:
> 
> 
>>[padraig at pixelbeat findul]$ cat input.txt
>>/lib/libthread_db-1.0.so
>>/usr/lib/gphoto/libgphoto_canon.so.0
>>/usr/lib/lib_alchemistmodule.so
>>
>>
>>OK I want to only show files in /lib/ or /usr/lib/
>>so I'm trying to exclude lines that have a / after
>>these 2 strings.
>>So try 1: Match 1 or more characters not /
>>
>>[padraig at pixelbeat findul]$ cat input.txt |
>>grep "\(^/usr/lib/[^/]+$\|^/lib/\)"
>>/lib/libthread_db-1.0.so
>>
>>This didn't match the last entry, why?
>>
> 
> 	Strange indeed. Interestingly
> 
> grep "\(^/usr/lib/[^/][^/]*$\|^/lib/\)" < input.txt
> 
> 	works. So it may be a bug ?


Intersting indeed.


 
> 	Out of curiousity - how come you didn't try something like
> 
> grep "^/\(usr/lib$\|^lib\)/[^/]+$" < input.txt


More correctly:

[padraig at pixelbeat findul]$ grep "^/\(usr/lib\|lib\)/[^/]*$" input.txt
/lib/libthread_db-1.0.so
/usr/lib/lib_alchemistmodule.so


[padraig at pixelbeat findul]$ grep -E "^/(usr/lib|lib)/[^/]+$" input.txt
/lib/libthread_db-1.0.so
/usr/lib/lib_alchemistmodule.so

Yes they are nicer, thanks.


> Good Luck,
> Mark.

cheers,
Padraig.