and directories created inside the directory we configure.
The Sticky bit works for directories in Linux.
When the Sticky bit is set, only the owners can delete their files.
To test this, you can run sudo mkdir accounting
The directory will be owned by root and the group as root.
The permissions for the User Owner are rwx.
The Group Owner is r-x
Other is r-x
Create the accounting group with sudo groupadd acconting
Change the accounting group directory’s group name.
sudo chown :accounting accounting
Now need to add the SGID bit and write permissions for the Group Owner.
sudo chmod 2770 accounting
The 2 is for SGID
Should then give us rwx for the root user.
rws for the accounting group.
--- for Other.
Plus SGID, which has the letter s (shown above) in the group position.
How do these SGID Bits affect directories?
The SGI Bits represent the only inheritance in standard Linux permissions and ownership.
For example, all files and directories created inside the accounting directory, will inherit the Group Owner, which in this case is the accounting group.
If user1 creates a file in the accounting directory, it will be owned by user1 and the accounting group.
Allows us to create a di rectory for group collaboration.
All users would need to belong to the accounting group to have write access.
To demonstrate in a terminal, we do sudo useradd -G accounting ted
-G is supplemental group
Provide ted a password with sudo passwd ted
Creates username called ted, which belongs to the accounting group.
Should see the accounting group at the bottom if run cat /etc/group
Will see ted added to the end of the line here as well.
Login as ted with su - ted
cd into the accounting directory.
Create a file with touch and you will see it owned by ted and the accounting group.
We add a Sticky bit, by adding a 1 to the left of the permissions.
For example sudo mkdir stickydir
Give all permissions to all people, including the Sticky bit as well.
sudo chmod 1777 stickydir
You will see the directory has a t in the execute position of Other.
This will be a lowercase t, if execute for Other is set.
Otherwise it will be an uppercase T.
The purpose of a Sticky Bit on a directory, is to keep users from deleting or moving each other’s files.
cd into the directory with cd /home/stickydir/
Then touch file.txt
Now give rwx permissions to everyone, with chmod 777 file.txt
Then change into another user, for example su - ted
The file file.txt has rwx for all users, so we have full accses, including delete.
If you then do rm file.txt, you will not be allowed to remove it.
The Sticky BIt is usually used for world-writable sticky directories, such as /tmp
You can verify this by typeing in ls -ld /tmp (the -ld is for directory). You should then see the t in the Other permissions section.