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In computing, the sticky bit is a user ownership access right flag that can be assigned to files and directories on Unix-like systems. When a directory's sticky bit is set, the filesystem treats the files in such directories in a special way so only the file's owner, the directory's owner, or root user can rename or delete the file. Without the sticky bit set, any user with write and execute permissions for the directory can rename or delete contained files, regardless of the file's owner. Typically this is set on the /tmp directory to prevent ordinary users from deleting or moving other users' files. Sticky bit, as a feature, was introduced in 4.3BSD in 1986 and today it is found in most modern Unix-like systems. ==History== The sticky bit was introduced in the Fifth Edition of Unix (in 1974) for use with pure executable files. When set, it instructed the operating system to retain the text segment of the program in swap space after the process exited. This speeds up subsequent executions by allowing the kernel to make a single operation of moving the program from swap to real memory. Thus, frequently-used programs like editors would load noticeably faster. One notable problem with "sticked" programs was replacing the executable (for instance, during patching); to do so required removing the sticky bit from the executable, executing the program and exiting to flush the cache, replacing the binary executable, and then restoring the sticky bit. Currently, this behavior is only operative in HP-UX and UnixWare. Solaris appears to have abandoned this in 2005. The 4.4-Lite release of BSD retained the old sticky bit behavior, but it has been subsequently dropped from OpenBSD (as of release 3.7) and FreeBSD (as of release 2.2.1). No version of Linux has ever supported this traditional behavior. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Sticky bit」の詳細全文を読む スポンサード リンク
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