Siege Lion on the Way (iii) Linux (11)---User and user groups, file permissions, directory configuration

First, user and user group:

3 Concepts: File owner (user), group, other person (others).

/etc/passwd <== to store all user names

/etc/shadow <== Store Personal password

/etc/group <== Store all the group names

Second, the concept of file permissions:

1. File attributes <== using Ls-al command

Drwxr-x---1 root root 4096 sep8 18:27 Install.log

①②③④⑤⑥⑦

Parameter description:

①: Permissions <== A total of 10 bits, the first digit represents the file type, and the next 9 bits three groups, respectively, representing the owner rights, user group permissions, other people permissions.

R: Readable;  W: writable; X: Executable or can enter the directory.

②: Number of inode connected to this file

③: Owner

④: User groups

⑤: File Size

2, how to modify the properties and permissions of the file? (Requires login with root permission)

CHGRP: Change the user group to which the file belongs. <== CHGRP Users Install.log

Chown: Change the file owner. <== chown Vbird Install.log

chmod: Change the permissions of the file.  <== chmod 777 Install.log; or chmod a+w Install.log

3, the file's permission meaning:

R: can be read.

W: You can edit, add, or modify the contents of a file, but you cannot create, delete, or rename files.

X: Executable.

4. The permission meaning of the directory:

R: Read the permissions of the directory structure list, you can use the LS command.

W: Change permissions on the directory structure list, such as new file or directory, delete, rename, move location, and so on.

X: Whether you can enter the directory to make it a working directory.

5. Types and extensions of Linux files:

A, file-, directory D, connection file L, block device file B, character device file C, socket s, Pipe F.

B, extension: The extension under Linux has no special meaning, just as a token, so that the user can know the purpose of the file.

C. The maximum length of a single file or directory name is 255 characters; The full path is a maximum of 4,096 characters.

D, the file name as far as possible to avoid some special symbols such as: *?><;&! []/\ ' "() {}+-, etc.).

Third, the directory configuration of Linux:

1. Directory Configuration standard: FHS

2, because the root directory/is important, so the directory should be as small as possible, because the larger the partition, the greater the chance of error.