Paul Miller wrote: > > I know this is a really stupid question.. but what is the sticky bit? >
The sticky bit overcomes a problem with file permissions in Unix. Specifically, the ability to create/delete a file in a given directory depends on the *directory permissions*. When the sticky bit is set, on a directory, the *owner* of files in that directory may remove the files. An example will make this clear. Suppose my system has a user, 'foo'. Let us assume the following commands are run by someone logged in as root: mylinux# cd ~foo mylinux# echo 'I dare you to delete this' > make_my_day mylinux# chmod 600 make_my_day mylinux# pwd /home/foo mylinux# ls -l make_my_day -rw------- 1 root root 0 Oct 1 11:11 /home/foo/make_my_day mylinux# Now user foo logs in and does the following: mylinux$ whoami foo mylinux$ pwd /home/foo mylinux$ cat make_my_day cat: make_my_day: Permission denied mylinux$ ls -ld . drwx--x--x 27 foo foo 3072 Oct 1 11:13 . mylinux$ rm make_my_day rm: remove `make_my_day', overriding mode 0600? y mylinux$ ls -l make_my_day ls: make_my_day: No such file or directory mylinux$ Suprised?! Don't be. In a unix file system a directory is basically a special "file". The act of creating or deleting a file from a directory consists (obviously there's a little more which must happen) of creating/removing "entries" in this special file. Thus it is the permissions on a *directory* which determine whether or not a file may be created-in/removed-from a directory. Anytime you want to have a directory be "shared" by many users, this type of behavior causes problems: if you make the directory writable, so that anyone can create a file in the directory, you also make it so that anyone can delete a file from the directory, *regardless* of who owns the file. Usually, what you want is for anyone (or anyone in a given group) to be able to be able to create file in the shared directory but only allow the *owner* of the file to delete (or modify) the file. The sticky bit makes this possible. -- Jens B. Jorgensen [EMAIL PROTECTED] -- TO UNSUBSCRIBE FROM THIS MAILING LIST: e-mail the word "unsubscribe" to [EMAIL PROTECTED] . Trouble? e-mail to [EMAIL PROTECTED] .