[ILUG] regular expression question

[Fergal Daly]

Under tcsh the grep dies with an error unless I change the "s to 's. This is 
because the shell sees $\ as a variable. Maybe in your shell $\ is not an 
unknown variable and so grep executes but does the wrong thing. Try replacing 
grep with echo and see if the regexp is printed out correctly.

Also, one thing that seems wrong is the fact that you only check the [^/]+ 
after /lib/ and not /usr/lib/.

As a Perl bigot, I think you should use egrep or grep -E to get rid of those 
backslashes too!

Anyway, this seems to do what you require

cat input.txt | grep -E '^(/usr/lib/|^/lib/)[^/]+$'

Fergal

On Tuesday 13 November 2001 16:15, 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?
>
> The following works but is not just robust?
> [padraig at pixelbeat findul]$ cat input.txt |
> grep "\(^/usr/lib/[^/]*$\|^/lib/\)"
> /lib/libthread_db-1.0.so
> /usr/lib/lib_alchemistmodule.so
>
> Padraig.