#  perl -e 'for(<access_log.*>){$a = $_; s/log/log.old/; `cp $a $_`}'
ls access_log.* | perl -pe 'chomp; $f0 = $_; s/log/log.old/; $_="cp $f0 $_\n"'
 # note: don't use $a
  # other ways to write it:
    # | perl -lne 'chomp; print "cp $_ $_.old"'
    # | perl -pe 's/.+/cp $& $&.old/'