[Dovecot] expire

[Papp Tamás]

hi!

$ dovecot --exec-mail ext /usr/lib/dovecot/expire-tool.sh
/usr/lib/dovecot/expire-tool.sh: 9: Bad substitution


What's the problem, do I miss something?
This is the first time, I trying to use expire.

This is an Ubuntu 10.04 .

Thank you,

tamas