Unix permissions are divided into three sections. User, Group, and Others or UGO

Under each group there are three permissions read, write, and execute or rwx.

You can find and show permissions of each file using ls -l or for a particular file: ls -l [filename.ext]

File permissions are 12 bits. Since they’re each set up as binary code. For example 110 in binary is 6 while 100 is 4. So you can easily dial a file permission setting like so via chmod.

Examples: 777 – rwx for all. 755 - rwx for owner, and rx for group and other. 744 – rwx,r,r: All permissions for owner, with read only for the rest And 444 r,r,r Or read only

Note that the default permissions for files and directories are 644 and 755 respectively.

And there are two versions of how read, write, and execute affect files and directories.

There are other commands to change file and folder permissions.

chmod to change permissions chgroup to change group permissions chown change ownership and group ownership of a file.

There are three special versions of permissions

setuid: Users who access the file is granted access permission of the owner of the file You can tell that setuid is active by looking for the s in rws. This means that the program always runs as root, no matter who started using the command.

Setgid: Similar to setud, but the process is changed to owner of the file. Setgid does three different unrelated things for executable, directories, and regular files.

Stickybit: A special permission that protect the files within a public writable directory Stickybit permission set the shared directory, user can create a files or directory But only by owner of the directory can modify or delete.

It's worth noting that setuid and setgid are potential security risk, but stickybit is a security boost.