Re: Problems using + with -f <file>

[Benno Schulenberg]

Julian Foad wrote:
> Gert Jan van Loo wrote:
> > If I change my pattern file to:
> > Input [a-zA-Z0-9_]\+ is unused
> > Now using "grep -f <patternfile> <source>" The patterns ARE
> > found. Now using "egrep -f <patternfile> <source>" The patterns
> > are NOT found.
> >
> > egrep seems to do the right thing.
> > I thought "[a-zA-Z0-9_]+" is part of the standard grep.
> > Even if it is not why does \+ suddenly work?
>
> All of this is working as intended,

Hmm, not quite:

$ echo "My source contains many of:
Input location is unused
Input rstn is unused" >file

$ grep --color "Input [A-Za-z]\+" file
Input location is unused
Input rstn is unused

Here "Input" and the word after it are red.

$ grep --color "Input [A-Z]\+" file
Input location is unused
Input rstn is unused

Now there is no color.  What is matched here?  Why are these lines 
getting printed?

Benno