File authority and detailed explanation of main subordinate group

1. File permissions 1. File attribute

two。 The permissions of files are mainly defined for three types of objects.

Owner: owner, u

Group: belonging to group, g

Other: other, o

3. Each file defines three permissions for each type of visitor.

R: Readable, read

W: Writable, write

X: eXcutable, execute

(1) for documents

R: you can use the file view class tool to get its contents

W: its content can be modified

X: you can ask the kernel to start this file as a process

(2) for catalogs

R: you can use ls to view a list of files in this directory

W: files can be created or deleted in this directory

X: you can use ls-l to view the file metadata in this directory (with r), and you can enter this directory by cd

X: only give directory x permission, not file x permission

4. File permission list

5. Modify file permissions command

(1) chmod [OPTION]... MODE [, MODE]... FILE...

MODE:

Modify all permissions for a class of users:

U = g = o = ug= a = upright department g =

Example:

Modify certain bit or bit permissions for a class of users

U + u-g + g-o + o-a + a-+-

Example:

(2) chmod [OPTION]... -- reference=RFILE FILE...

Refer to the permissions of the RFILE file, and modify FILE to be the same as RFILE

Example:

(3) chmod [OPTION]... OCTAL-MODE FILE...

Parameters and examples:

-R: recursively modify permissions

(4) modify permissions according to the numerical representation in the file permission list

Example:

Second, document owners and subordinate groups 1. The owner of the modified file: chown

(1) chown [OPTION]... [OWNER] [: [GROUP]] FILE...

Usage:

OWNER

OWNER:GROUP

: GROUP

Note: the colon in the command is available. Replace

-R: recursive

(2) chown [OPTION]... -- reference=RFILE FILE...

two。 Modify the group of the file: chgrp

Previously, you have demonstrated changing the owner while changing the group through the chown command. The following shows the command to change the group separately.

(1) chgrp [OPTION]... GROUP FILE...

(2) chgrp [OPTION]... -- reference=RFILE FILE...

(3)-R recursion