4.3BSD-UWisc/man/cat8/sticky.8

STICKY(8)           UNIX Programmer's Manual            STICKY(8)



NAME
     sticky - persistent text and append-only directories

DESCRIPTION
     The _s_t_i_c_k_y _b_i_t (file mode bit 01000, see _c_h_m_o_d(2)) is used
     to indicate special treatment for certain executable files
     and directories.

STICKY TEXT EXECUTABLE FILES
     While the `sticky bit' is set on a sharable executable file,
     the text of that file will not be removed from the system
     swap area.  Thus the file does not have to be fetched from
     the file system upon each execution.  Shareable text seg-
     ments are normally placed in a least-frequently-used cache
     after use, and thus the `sticky bit' has little effect on
     commonly-used text images.

     Sharable executable files are made by the -n and -z options
     of _l_d(1).

     Only the super-user can set the sticky bit on a sharable
     executable file.

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 direc-
     tory 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 oth-
     ers' files.

     Any user may create a sticky directory.  See _c_h_m_o_d(1) for
     details about modifying file modes.

BUGS
     Since the text areas of sticky text executables are stashed
     in the swap area, abuse of the feature can cause a system to
     run out of swap.

     Neither _o_p_e_n(2) nor _m_k_d_i_r(2) will create a file with the
     sticky bit set.










Printed 12/27/86          May 26, 1986                          1