sticky



STICKY(8)                   System Manager's Manual                  STICKY(8)


NAME

     sticky - sticky text and append-only directories


DESCRIPTION

     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

     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

     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

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


BUGS

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

OpenBSD 6.4                    February 14, 2014                   OpenBSD 6.4

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