Is there a way to obtain patterns in one file (a list of patterns) from another file using ack as the -f option in grep? I see there is an -f option in ack but it's different with the -f in grep.

Perhaps an example will give you a better idea. Suppose I have file1:

file1:
a
c
e

And file2:

file2:
a  1
b  2
c  3
d  4
e  5

And I want to obtain all the patterns in file1 from file2 to give:

a  1
c  3
e  5

Can ack do this? Otherwise, is there a better way to handle the job (such like awk or using hash) because I have millions of records in both files and really need an efficient way to complete? Thanks!