STICKY(8) 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 execu‐ tion. Shareable text segments are normally placed in a least-fre‐ quently-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 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 _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. 4th Berkeley Distribution May 26, 1986 STICKY(8)