Users and Groups

• Every user is a member of at least one group (/etc/group);
• sys-admin, root is privileged (cf. Administrator in MS Windows).

Files and Directories

Every file and directory has

• read, write, execute permission for
• owner, group, world.

Example

  prompt> ls -l

  drwxr-xr-x   3 simonh users   4096 Oct 20 10:14 .
  drwxr-xr-x  42 root   root    8192 Oct 15 18:05 ..
  -rwxr-x---   1 simonh users 661327 Feb 14  2008 a.out
  -rw-r--r--   1 simonh users   2102 Feb 13  2008 f02gjfe.f
  drwxr-xr-x   2 simonh users   4096 Oct 20 10:14 scratch
  -rw-r--r--   1 simonh users   5688 Feb 13  2008 test_nag_pgi.f