The Sticky Bit

One last special permission bit I want to talk about is the sticky bit.

This permission bit, "sticks a file/directory" this means that only the owner or the root user can delete or modify the file. This is very useful for shared directories. Take a look at the example below:

$ ls -ld /tmp
drwxrwxrwxt 6 root root 4096 Dec 15 11:45 /tmp

You'll see a special permission bit at the end here t, this means everyone can add files, write files, modify files in the /tmp directory, but only root can delete the /tmp directory.

Modify sticky bit

$ sudo chmod +t mydir

$ sudo chmod 1755 mydir

The numerical representation for the sticky bit is 1