merging two files

Question

I have two files (tab delimited) one file is has 4 columns and n number of rows and second file has 2 columns and n number of rows.

column 4 of first file is identic

Answer 1

For tabulator try

join -t \t files1 …

Answer 2

Have a look at the join command, see guide here

Answer 3

try with join

join FILE1 FILE2 -1 4 -2 2 -t"tab"

to express a join between the files FILE1 and FILE2 based on the 4th field (-1 4) of FILE1 and the 2nd field (-2 2) of FILE2