UNIX for Advanced & Expert Users

filetime()
{
perl -e '      
      $mtime = (stat("$ARGV[0]"))[9];

      # time structure into variables

      ($sec,$min,$hr,$day,$mon,$yr,$wday,@dntcare) = localtime($mtime);
      $yr = ($yr>=70) ? $yr+1900 : $yr+2000;

      printf ("%d%02d%02d%02d%02d", $yr,$mon,$day,$hr,$min); ' "$1"
}
for fname in *.dat
do
# get file time in YYYYMMddhhmm format
   oldtime=$(filetime $fname)
   ls -l $fname
# sed your file here
#  sed 's/  / /g' $fname > tmp; mv tmp $fname
# put filetime back to where it was
  touch -t $oldtime $fname
  ls -l $fname
done