Linux Combine two files by column

Question

I am trying to combine two files as below (Intersection)

ID     Name  Telephone       
1      John     011
2      Sam      013
3      Jena     014
4      Pet         


        

Answer 1

$ awk -v OFS='\t' '
NR==1   { print $0, "Remark1", "Remark2"; next }
NR==FNR { a[$1]=$0; next }
$1 in a { print a[$1], $2, $3 }
' Test1.txt Test2.txt
ID     Name  Telephone  Remark1 Remark2
1      John     011     Test1   Test2
2      Sam      013     Test3   Test4
3      Jena     014     Test5   Test6
4      Peter    015     Test7   Test8