Home Man
Today's Posts

Linux & Unix Commands - Search Man Pages
Man Page or Keyword Search:
Select Section of Man Page:
Select Man Page Repository:

NetBSD 6.1.5 - man page for sticky (netbsd section 7)

STICKY(7)		       BSD Miscellaneous Information Manual			STICKY(7)

     sticky -- Description of the `sticky' (S_ISVTX) bit functionality

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

   Sticky files
     For regular files, the use of mode S_ISVTX is reserved and can be set only by the super-
     user.  NetBSD does not currently treat regular files that have the sticky bit set specially,
     but this behavior might change in the future.

   Sticky directories
     A directory whose ``sticky bit'' is set becomes a directory in which the deletion of files
     is restricted.  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 super-user.  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

     The sticky bit first appeared in V7, and this manual page appeared in section 8.  Its ini-
     tial use was to mark sharable executables that were frequently used so that they would stay
     in swap after the process exited.	Sharable executables were compiled in a special way so
     their text and read-only data could be shared amongst processes.  vi(1) and sh(1) were such
     executables.  This is where the term ``sticky'' comes from - the program would stick around
     in swap, and it would not have to be fetched again from the file system.  Of course as long
     as there was a copy in the swap area, the file was marked busy so it could not be overwrit-
     ten.  On V7 this meant that the file could not be removed either, because busy executables
     could not be removed, but this restriction was lifted in BSD releases.

     To replace such executables was a cumbersome process.  One had first to remove the sticky
     bit, then execute the binary so that the copy from swap was flushed, overwrite the exe-
     cutable, and finally reset the sticky bit.

     Later, on SunOS 4, the sticky bit got an additional meaning for files that had the bit set
     and were not executable: read and write operations from and to those files would go directly
     to the disk and bypass the buffer cache.  This was typically used on swap files for NFS
     clients on an NFS server, so that swap I/O generated by the clients on the servers would not
     evict useful data from the server's buffer cache.

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

BSD					   May 10, 2011 				      BSD

All times are GMT -4. The time now is 05:16 AM.

Unix & Linux Forums Content Copyrightę1993-2018. All Rights Reserved.
Show Password