$ regexpand "(\([:num:]{3}\)-[:num:]{3}-[:num:]{4} ){2}" | head -10
(000)-000-0000 (000)-000-0000
(000)-000-0000 (000)-000-0001
(000)-000-0000 (000)-000-0002
(000)-000-0000 (000)-000-0003
(000)-000-0000 (000)-000-0004
(000)-000-0000 (000)-000-0005
(000)-000-0000 (000)-000-0006
(000)-000-0000 (000)-000-0007
(000)-000-0000 (000)-000-0008
(000)-000-0000 (000)-000-0009
$ regexpand "(a|b)*c+"
c
cc
ac
acc
bc
bcc
aac
aacc
abc
abcc
bac
bacc
bbc
bbcc
aaac
aaacc
aabc
aabcc
abac
abacc
abbc
abbcc
baac
baacc
babc
babcc
bbac
bbacc
bbbc
bbbcc