R-beta: POSIX regular expressions not available !?

[Hubert Palme]

When trying grep(), I get the following:

> grep("[a-z]", letters)
Error in grep(pattern, x, ignore.case, extended, value) : POSIX regular expressions not available

I can't find any pointer in the installation kit. How can I configure
R to make it "avaliable"?

I run R in an Irix 5.3 system.

Thanks in advance!

-- 
======================================================================
Hubert Palme         Bergische Universitaet-Gesamthochschule Wuppertal
                                      Computing  Center
                                      D-42097 Wuppertal
Email: palme at uni-wuppertal.de             (Germany)
http://www.hrz.uni-wuppertal.de/hrz/personen/h_palme.html
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