Novell LINUX ENTERPRISE SERVER 10 - INSTALLATION AND ADMINISTRATION 11-05-2007, Руководство по установке

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The next three blocks follow a standard pattern. The first three characters refer to
whether the file is readable (
r
) or not (
–
). A
w
in the middle portion symbolizes
that the corresponding object can be edited and a hyphen (
–
) means it is not possible
to write to the file. An
x
in the third position denotes that the object can be executed.
Because the file in this example is a text file and not one that is executable, exe-
cutable access for this particular file is not needed.
In this example,
tux
has, as owner of the file
Roadmap
, read (
r
) and write access
(
w
) to it, but cannot execute it (
x
). The members of the group
project3
can read
the file, but they cannot modify it or execute it. Other users do not have any access
to this file. Other permissions can be assigned by means of ACLs (access control
lists).
Directory Permissions
Access permissions for directories have the type
d
. For directories, the individual
permissions have a slightly different meaning.
Example 17.2 Sample Output Showing Directory Permissions
drwxrwxr-x 1 tux project3 35 Jun 21 15:15 ProjectData
In Example 17.2, “Sample Output Showing Directory Permissions” (page 345), the
owner (
tux
) and the owning group (
project3
) of the directory
ProjectData
are easy to recognize. In contrast to the file access permissions from File Access
(page 344), the set reading permission (
r
) means that the contents of the directory
can be shown. The write permission (
w
) means that new files can be created. The
executable permission (x) means that the user can change to this directory. In the
above example, the user
tux
as well as the members of the group
project3
can
change to the
ProjectData
directory (
x
), view the contents (
r
), and add or
delete files (
w
). The rest of the users, on the other hand, are given less access. They
may enter the directory (
x
) and browse through it (
r
), but not insert any new files
(
w
).
17.2.2 Modifying File Permissions
Changing Access Permissions
The access permissions of a file or directory can be changed by the owner and, of
course, by
root
with the command
chmod
followed by the parameters changing
the permissions and one or more filenames. The parameters form different cate-
gories:
Working with the Shell 345