UNIX for Dummies Questions & Answers

file1

- a b
a 1 2
b 3 4

file2

- a b
a 5 6
b 7 8

file3

- a b
a 9 10
b 11 12


Final output

var1 var2 file1 file2 file3      
a a 1 5 9
a b 2 6 10
b a 3 7 11
b b 4 8 12

awk '
  FNR>1{
    H[FNR]=$1
    for(i=2; i<=NF; i++)
      A[i,FNR]=A[i,FNR] OFS $i
  }
  END{
    for(i=2; i<=FNR; i++)
      for(j=2; j<=FNR; j++)
        print H[i], H[j] A[j,i]
  }
' file*