Shell Programming and Scripting

colA	colB	colC	colD	colE
10	11	12	13	15
14	14	14	14	16

col1 	col2 	col3	col4	col5	col6
1	2	3	4	9	45
5	6	7	8	9	46

col5	colA
col4	colC
col2 	colD
col1	colB

colA	colB	colC	colD	col3	col6
9	1	4	2	3	45
9	5	8	6	7	46

awk '  FILENAME=="names" { n[$1]=$2;next }
       FILENAME=="oldfile"  && NR==1 { for (i=1;i<=NF;i++) o[i]=$i ; next }
       FILENAME=="newfile" && NR==1 {  s=x; for (i=1;i<=NF;i++) { 
       						for ($i in n) {
       							$i=n[$i] }
       						s=s FS n[$i]
       						{
       				       print s
       				     }' names oldfile newfile

awk '
FNR==1 { file++ }
file==1 { new[$1]=$2; next }
file==2 {
  if(FNR==1) for(i=1;i<=NF;i++) old[i]=$i
  next
}
file==3&&FNR==1 {
    for(i=1;i<=NF;i++)
        if($i in new) {
            check=h
            for(j=1;j in old;j++) if(old[j]==new[$i]) { pos[j]=i; h++}
            if(check==h) {
                print "Error: cannot update field \"" $i "\": field \"" new[$i] "\" not found in oldfile" > "/dev/stderr"
                exit 1
            }
        }
        for(i=1;i<=NF;i++)
        if($i in new) $i=new[$i]
        else pos[++h]=i
}
{
   out=$(pos[1])
   for(i=2;i<=NF;i++) out= out FS $(pos[i])
   print out
}' names oldfile newfile