[COFF] Requesting thoughts on extended regular expressions in grep.
Ralph Corderoy
ralph at inputplus.co.uk
Sat Mar 4 20:26:51 AEST 2023
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.
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