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.
