serious awk bug

[Magnus Gislason]

tps at chem.ucsd.edu (Tom Stockfisch) writes:
>The following awk script doesn't behave properly:
>#! /bin/sh
>awk '/^a*[^b]/	{  print "1:", $0 }
>/^a*b/ 	{ print "2:", $0 }
>'
[stuff deleted]
>Basically, the line "ab" should match only rule 2, but it matches both
>rules.  The following script:

In Regular Expressions `a*' meens 0 or more occurrencies of `a' and
`[^b]' meens any character except `b'.  In this case `a*[^b]' matches
0 `a's followed by a character that is not `b' (in this case `a').

I tried this with grep, egrep, sed and vi and they all behaved like awk
so I suppose it's the correct way.