sticky text and append-only directories
A special file mode, called the sticky bit (mode S_ISTXT), is
used to indicate special treatment for directories. It is ignored for regular
or the file
an explanation of file modes.
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
for details about modifying file modes.
sticky command appeared in
Version 32V AT&T UNIX.