File and directory attributes

The system handles files and directories in the same way; directories are just specialized files, containing other files and directories rather than program code or text. Files and directories both have a name, a path, and a set of attributes. Internally, the system keeps track of files and directories using inodes, or index nodes. See ``How the system manages files and directories''.

A simple way of checking some of the attributes of a file or directory is the long listing, obtained using the -l option to the ls(C) command (or just l):

What you see in a long listing

• The first field (file type) indicates the sort of file that is present in the listing. The following codes are some of those used (for a full list, see ls(C)):

  
  -

  ordinary file

  
  b

  block special file

  
  c

  character special file

  
  d

  directory

  
  l

  symbolic link

  
  p

  named pipe

• The second field (permissions) shows who is permitted to read, write, or execute a file, or change to a directory. Users are split into the file's owner, people in the same work group as the owner, and other people. A separate set of permissions is maintained for each category. The notation used here is explained in detail in ``Access control for files and directories''.

• The third field (links) shows the number of links that exist for the file (links are discussed in ``Creating links to files and directories'' ).

• The fourth field (owner) shows the login name of the owner of the file.

• The fifth field (group) shows the group to which the file belongs; that is, the group of users who have ``group'' access permission to the file. See ``Finding out your group'' for an explanation of groups.

• The sixth field (size) shows the number of bytes in the file.

• The seventh and eighth fields (date and time of last modification) show the date and time when the file was last modified.

• The final field (filename) shows the name of the file. See ``Filenaming conventions'' for more on filenames.