Columns are defined as byte-wise offsets in a row or line and specification of columns can take one of the following three forms:

start-

print from the start column to the end of the line.

-end

print from the beginning of the line up to and including the end column.

start-end

print from the start column up to and including the end column.

$ cat junk
123456789

$ getcols 3-7 < junk
34567

$ getcols -4 < junk
1234

$ getcols 6-6 < junk
6