diff --git a/files_directories/chmod.md b/files_directories/chmod.md
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+We are aware of permissions for the owner(u), group(g), and other(o), however
+the set-uid, set-gid and sticky bit are other special permissions.
+
+| setting | description |
+| set-uid | setting uid on an executable file allows the file to be executed
+with the original owners permissions.e.g.A script owned by root is executed
+with root priviledges when run by an ordinary user|
+|set-gid  | in files, set-gid files are executed with the group's permissions,
+while in directories all new files belong to the group by default|
+|sticky bit | In a shared environment, allows deletion only by the owner of the
+file|
+
+```
+chmod u+s file  # sets uid, use - to unset
+chmod g+s directory # sets gid
+chmod +t   # sets the sticky bit
+chmod 1770 directory # sets sticky bit, grants rwx permissions for u and g
+```