Originally Posted by bartus11

Code:

join -t, -11 -22 -o1.1,1.2,2.3 1940births.csv ethnicity.csv

"join" is a standard Unix/Linux utility to join files based on common field.

Originally Posted by pravin27

Code:

awk -F"," 'NR==FNR{a[$1]++;next}a[$2]' 1940births.csv ethnicity.csv

NR The total number of input records seen so far.
FNR The input record number in the current input file,FNR restarts the counting at the begining of each input file.

Code:

if NR==FNR then {a[$1]++;next}

# Process the first file(1940births.csv), fill the array 'a' with index as $1 of 1940births.csv

Code:

else a[$2]

' # process the second file(ethnicity.csv),if $2 of second file is present in array 'a' then print the current record for second file

Code:

1940births.csv ethnicity.csv

# input files