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

Hi, I'd like some thoughts ~> input on extended regular expressions used with grep, specifically GNU grep -e / egrep. What are the pros / cons to creating extended regular expressions like the following: ^\w{3} vs: ^(Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec) Or: [ :[:digit:]]{11} vs: ( 1| 2| 3| 4| 5| 6| 7| 8| 9|10|11|12|13|14|15|16|17|18|19|20|21|22|23|24|25|26|27|28|29|30|31) (0|1|2)[[:digit:]]:(0|1|2|3|4|5)[[:digit:]]:(0|1|2|3|4|5)[[:digit:]] I'm currently eliding the 61st (60) second, the 32nd day, and dealing with February having fewer days for simplicity. For matching patterns like the following in log files? Mar 2 03:23:38 I'm working on organically training logcheck to match known good log entries. So I'm *DEEP* in the bowels of extended regular expressions (GNU egrep) that runs over all logs hourly. As such, I'm interested in making sure that my REs are both efficient and accurate or at least not WILDLY badly structured. The pedantic part of me wants to avoid wildcard type matches (\w), even if they are bounded (\w{3}), unless it truly is for unpredictable text. I'd appreciate any feedback and recommendations from people who have been using and / or optimizing (extended) regular expressions for longer than I have been using them. Thank you for your time and input. -- Grant. . . . unix || die