Shell Programming and Scripting

file1.txt

joe 1 4 5 6 7 3
manny 2 3 4 5 6 7

file2.txt

bob 1 5 6 7 4 3
larry 2 4 3 2 1 2

file1 joe 1 4 5 6 7 3
file 1 manny 2 3 4 5 6 7
file 2 bob 1 5 6 7 4 3
file 2 larry 2 4 3 2 1 2

#!/bin/ksh

set -A afFile "file1" "file2" "file3"
typeset -i iFileCnt=0

while [ $iFileCnt -lt ${#afFile[*]} ] ; do
     sed 's/^/'"${afFile[$iFileCnt]}"'<tab>/' "${afFile[$iFileCnt]}"
     (( afFile += 1 ))
done

exit 0

$ awk '{print FILENAME,$0}' file1 file2