how to call unix command in expect script?

[emily_3]

hello,

I want to run unix command in expect script. As known I need to use "exec" to call, so I write the script as following, it tried to grep string aaaa in file /tmp/test. but it always failed. Can you help on this?
exec grep 'aaaa' /tmp/test
My question is that whether "exec" can call for any unix command? Can I relove this without using unix command? Thanks.

[Steven Schweda]

You might get more and better answers in one
of the UNIX forums than you will in this VMS
forum.

[emily_3]

thanks, I will repost this msg at VMS forum.