쉘 스크립트에서 가장 마지막 파일

$ man ls | grep sort
       Sort entries alphabetically if none of -cftuvSUX nor --sort  is  speci?
       -c     with -lt: sort by, and show, ctime (time of last modification of
              file status information); with -l: show ctime and sort by  name;
              otherwise: sort by ctime, newest first
       -f     do not sort, enable -aU, disable -ls --color
              can   be  augmented  with  a  --sort  option,  but  any  use  of
              --sort=none (-U) disables grouping
              reverse order while sorting
       -S     sort by file size, largest first
       --sort=WORD
              sort  by  WORD instead of name: none (-U), size (-S), time (-t),
              specified time as sort key if --sort=time (newest first)
       -t     sort by modification time, newest first
       -u     with  -lt:  sort by, and show, access time; with -l: show access
              time and sort by name; otherwise: sort by  access  time,  newest
       -U     do not sort; list entries in directory order
       -v     natural sort of (version) numbers within text
       -X     sort alphabetically by entry extension

$ grep "xx" $(ls -v dd* | tail -1)