[COFF] Re: Requesting thoughts on extended regular expressions in grep.

[Ralph Corderoy <ralph@inputplus.co.uk>]

Hi Grant,

> the more precise alternation listing out each month. (Jan|Feb|Mar...

For those regexp engines which test each alternative in turn, ordering
the months most-frequent first would give a slight win.  :-)  It really
is a rabbit hole once you start.  Typically not worth entering, but it
can be fun if you like that kind of thing.

> I trust that syslog will produce consistent line beginnings more than
> I trust the data that is provided to syslog.  But I'd still like to be
> able to detect "Jer" or "Dot" if syslog ever tosses it's cookies.

You could develop your regexps to find lines of interest and then flip
them about, e.g. egrep's -v, to see what lines are missed and consider
if any are interesting.  Repeat.  But this happens at development time.

Or at run time, you can have a ‘loose’ regexp to let all expected lines
in through the door and then match with one or more ‘tight’ regexps,
baulking if none do.

There's no right answer in general.

-- 
Cheers, Ralph.