Describe JoinFiles here. Join two files on a common field and re-arrange the output: {{{ $ cat a.txt cust1, ac1, 100 cust2, ac2, 200 $ cat b.txt 100000, cust1, 100 2000000, cust2, 200 $ join -a 1 -a 2 -1 3 -2 3 -t"," -o 1.1 1.2 1.3 2.1 a.txt b.txt cust1, ac1, 100,100000 cust2, ac2, 200,2000000 }}}