serious awk bug

[Randal Schwartz]

In article <702 at chem.ucsd.EDU>, tps at chem (Tom Stockfisch) writes:
| 
| The following awk script doesn't behave properly:
| 
| #! /bin/sh
| 
| awk '/^a*[^b]/	{  print "1:", $0 }
| /^a*b/ 	{ print "2:", $0 }
| '
| 
| When given the following input
| 
| b
| ab
| 
| It produces the following output
| 
| 2: b
| 1: ab
| 2: ab
| 
| Basically, the line "ab" should match only rule 2, but it matches both
| rules.

[This doesn't belong in WIZARDS.  Sorry.]

But, it *does* match rule 1!  Look carefully.  If you take zero 'a's,
and one 'not b', you can get line "ab"!

In Perl:

perl -ne 'print "1: $_" if /^a*[^b]/; print "2: $_" if /^a*b/;' <<EOF
b
ab
EOF

produces:

2: b
1: ab
2: ab

Just like awk.  Amazing.

No problem.

Just another Perl and awk hacker,
-- 
/=Randal L. Schwartz, Stonehenge Consulting Services (503)777-0095 ==========\
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