디렉토리와 그 안에서 sticky bit가 설정된 파일 삭제 여부에 대해

$ man chmod

RESTRICTED DELETION FLAG OR STICKY BIT
  The restricted deletion flag or sticky bit is a  single  bit,  whose
  interpretation  depends  on the file type.  For directories, it pre‐
  vents unprivileged users from removing or renaming  a  file  in  the
  directory  unless they own the file or the directory; this is called
  the restricted deletion flag for  the  directory,  and  is  commonly
  found on world-writable directories like /tmp.  For regular files on
  some older systems, the bit saves the program's text  image  on  the
  swap  device  so  it will load more quickly when run; this is called
  the sticky bit.