freebsd man page for sticky

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

NAME
     sticky -- sticky text and append-only directories

DESCRIPTION
     A special file mode, called the sticky bit (mode S_ISTXT), is used to indicate special treatment for directories.	It is ignored for regular
     files.  See chmod(2) or the file <sys/stat.h> for an explanation of file modes.

STICKY DIRECTORIES
     A directory whose `sticky bit' is set becomes an append-only directory, or, more accurately, 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 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.

BSD
								   June 5, 1993 							       BSD