Re: Egrep does not support \A, \Z, \s

[Andreas Schwab]

David Grayson <address@hidden> writes:

> I have GNU grep version 2.5 for linux.
>  
> It seems like it does not support regular expressions properly because
> it does not recognize slash characters.  In particular, the following
> commands produce no output:
>
> echo "hi" | egrep "\Ah"
> echo "hi | egrep "i\Z"
> echo "h i" | egrep "\s"
>
> Maybe this isn't grep's fault.

POSIX says:

  The ERE grammar does not permit several constructs that previous sections
  specify as having undefined results:

  • ORD_CHAR preceded by ’\’

  [...]

  Implementations are permitted to extend the language to allow
  these. Conforming applications cannot use such constructs.

Thus your regepxs are malformed.

Andreas.

-- 
Andreas Schwab, SuSE Labs, address@hidden
SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."