Intro to UNIX

File Permissions

• Every file has 9 permission bits. They are grouped in threes: read/write/execute (or, for directories, read/write/cd).

  owner permissions	Does the owner have read/write/execute permissions?
  group permissions	Do other members of the same group have read/write/execute permissions?
  world permissions	Does anyone (or any program) with an account on this machine have read/write/execute permissions?

• To check a file's permissions: ls -l filename
  • The first character shows whether it is a file or directory
  • The next 3 characters show the owner permissions
  • The next 3 characters show the group permissions
  • The next 3 characters show the world permissions
  • Examples:

            -rw-rw-r-- filename
            -rwxrwxr-- filename
            -rw------- filename
            drwxrwxr-x directoryName
            

• To change a file's permissions: man chmod