There are some unix commands for seeing information about files:

• file filename: gives information about the file type.
• stat filename: lists lots of information about a file.
  (to create a symbolic link use ln: ln -s filename symlink_name)
• ls -il: ls with inode numbers
• df lists space info and mount points for each mounted file system
• du lists disk space usage for a subtree of the filesytem

Try these out on different types of file (both for different Unix types, but also for different contents of Unix regular files):

  file foo.c         # ascii file
  file a.out         # binary executable file
  file report.pdf    # pdf file
  file cs45          # directory
  file /usr/bin/vim  # symbolic link
  file /dev/mailbox2 # device files

  stat /usr/bin/vim
  stat foo.c
  stat cs45
  stat file.pdf 
  stat /dev/mailbox2

  stat -f /local                 # -f: lists information about the filesytem
  stat -f /home/your_user_name

  df -h -c           # try from your home directory and then from a subdirectory

There is more information about examining system state off my help pages (0S/Arch Links: "tools for examining system state")