Awk for handling three files - awk

Question

Input:
File 1
col1 col2 col3 col4 col5 col6 col7
A 91 - E Abu 7 -
B 82 - f Anu 9 -
C 93 - G Aru 8 -
File 2
col1 col2 col3 col4 col5 col6 col7
A 91 - x Bob 7 -
B 82 - y Bag 9 -
C 93 - z Bui 8 -
File 3
col1 col2 col3 col4 col5 col6 col7
A 91 - T Can 7 -
B 82 - U Con 9 -
C 93 - V Cuu 8 -
Output Expected:
col1 col2 col3 col4 col5
A 91 Abu Bob Can
B 82 Anu Bag Cun
C 93 Aru Bui Cuu
I have three files having same data at col1 and 2. I need to print fifth column of all files along with first two column.
I am able to do using two files. So Can anyone help me to do with three and more files?

Answer 1

Here is one way using awk:
$ awk '
BEGIN {
SUBSEP = FS;
print "col1 col2 col3 col4 col5"
}
FNR>1 {
a[$1,$2] = (a[$1,$2]?a[$1,$2]FS$5:$5)
}
END {
for(x in a) print x, a[x]
}' file1 file2 file3
col1 col2 col3 col4 col5
C 93 Aru Bui Cuu
A 91 Abu Bob Can
B 82 Anu Bag Con
You can pipe the output to sort if you required sorted output. This does not limit to three files. It is scalable to n number of files. Just add the file names at the end or use * to glob to all files under a given directory.

Answer 2

Assuming all three files have same number of rows because of this sentence
I have three files having same data at col1 and 2.
awk 'BEGIN{OFS="\t";
getline<"file1";getline<"file2";getline<"file3";
print "col1","col2","col3","col4","col5";
while(1) {getline < "file1";a=$1;b=$2;c=$5;getline<"file2";d=$5;f=getline<"file3";e=$5;
if(!f)exit;print a,b,c,d,e}}'
Output:
col1 col2 col3 col4 col5
A 91 Abu Bob Can
B 82 Anu Bag Con
C 93 Aru Bui Cuu
This will discard first line of each file, then reads files line by line, printing desired fields.