Re: gawk: {} repetition in patterns doesn't work?

[tt]

address@hidden (Paul Eggert) writes:

> > echo 'aa' | awk '/a{2}/' 

> The POSIX requirement is widely ignored, because it causes problems
> with patterns that contain stray '{' characters.

> gawk should do what GNU grep does: namely, support the POSIX
> requirement only when it is absolutely required, and otherwise treat
> stray braces as literal braces.  POSIX allows this behavior.  Here is
> a quote from the grep manual that should help explain things better:
> 
>       GNU `egrep' attempts to support traditional usage by assuming that
>    `{' is not special if it would be the start of an invalid interval
>    specification.  For example, the shell command `egrep '{1'' searches
>    for the two-character string `{1' instead of reporting a syntax error
>    in the regular expression.  POSIX.2 allows this behavior as an
>    extension, but portable scripts should avoid it.
> 
> On my list of things to do is to add support for this to GNU regexp.c.
> That should make it easy to fix gawk to be POSIX-compliant here.

That would indeed give the best of both worlds!

Thank you for the explanation,

-- 
Tapani Tarvainen