Special Permissions (Setuid, Setgid, Sticky Bit)

Setting Setuid Permission

The setuid permission allows a program to run with the permissions of the file owner.

chmod u+s file

• u+s: This sets the setuid permission for the user.

For example, to set the setuid permission on an executable file named program, you can use:

chmod u+s program

Setting Setgid Permission

The setgid permission ensures that files created in a directory inherit the group ownership of the directory, rather than the user’s default group.

chmod g+s directory

• g+s: This sets the setgid permission for the group.

For example, to set the setgid permission on a directory named shared, you can use:

chmod g+s shared

Setting the Sticky Bit

The sticky bit ensures that only the file owner can delete or rename their files in a directory.

chmod +t directory

• +t: This sets the sticky bit.

For example, to set the sticky bit on a directory named uploads, you can use:

chmod +t uploads

These commands and options are fundamental to managing permissions on a Linux system. Understanding them allows you to control access and secure your system effectively.