LinuxPapers.org: File Permissions in Unix and Linux

[ Thanks to [email protected]
for this link. ]

“This article describes the basic notions around file
permissions in Unix and GNU/Linux, giving the reader the knowledge
to use them effectively”

“In every computer that has a Unix-like operative system, such
as GNU/Linux, many different users are able to access the system.
In order to guarantee the security and the privacy of each user’s
data, the operative system is equipped with mechanisms that allow
us to manage the permissions associated with every element in the
filesystem, the files and directories. For each of these elements
there is an owner and a group: the owner is the user that the file
or directory belongs to, and the group is a particular group of
users that in general are able to access that file or

“The file permissions for test_file, are shown by the first 10
symbols in the output from ls. The first symbol, in the case of
files, is always -, while the remaining nine symbols describe the
permissions that are associated with the file. Those nine symbols
are divided into three groups of three (from left to right):

  • permissions for the user that owns the file
  • permissions for the users in the file’s group
  • permissions for all other users in the system”