NAME    [Toc]    [Back]

     sticky - sticky text and append-only directories

DESCRIPTION    [Toc]    [Back]

     A special file mode, called the sticky bit  (mode  S_ISVTX),
is used to indicate
  special  treatment  for  files and directories.  See
chmod(2) or the
     file /usr/include/sys/stat.h  for  an  explanation  of  file
modes.

STICKY FILES    [Toc]    [Back]

     Historically,  an  executable  shareable  file which had the
sticky bit set
     was not immediately discarded from swap space  after  execution.  The kernel
  hoarded  the text segment of the file for future reuse,
thus avoiding
     having to reload the program.  This is  no  longer  true  on
modern systems;
     the  current  virtual  memory system keeps track of recently
used executables,
 making the sticky bit for files redundant.  The sticky
bit can
     still be set on files, but without any effect.

     Only  the superuser can set the sticky bit on a file, though
the owner of
     the file may clear the sticky bit.

STICKY DIRECTORIES    [Toc]    [Back]

     A directory with the `sticky bit' set places restrictions on
file deletion:
  a  file  in a sticky directory may only be removed or
renamed by a
     user if the user has write permission for the directory  and
the user is
     the  owner  of  the file, the owner of the directory, or the
superuser.
     This feature is usefully applied to directories such as /tmp
which must
     be  publicly  writable  but should deny users the license to
arbitrarily
     delete or rename each others' files.

     Any user may create a sticky directory.   See  chmod(1)  for
details about
     modifying file modes.

HISTORY    [Toc]    [Back]

     A sticky command appeared in Version 32V AT&T UNIX.

BUGS    [Toc]    [Back]

     Neither  open(2)  nor  mkdir(2)  will create a file with the
sticky bit set.

OpenBSD      3.6                           June      5,      1993