Linux Study Notes - Part 5
(Disclaimer: This note is only for study records and reference)
A Linux directory or file will have an owner and a group. The owner is the owner of the file, and the group refers to which group the file belongs to.
File properties:
d rwxr-xr-x 2 root root 6 2月 18 10:52 dic
1 2 3 4 5 6 7 8 9 10
1: Used to describe the file type:
d: is the directory
-: Indicates that the file is a normal file
l: means as a link file
b: It is a block device, such as /dev/sda, the disk partition file is this type
c: Represented as serial port device file, such as keyboard, mouse, etc.
s: represented as a socket file for communication between processes
2: The first 3 digits are owner permissions, the middle 3 digits are ownership permissions, and the last 3 digits are other user permissions (you must have x permissions to open and view the directory)
3: Occupied node: if it is a directory, the value is related to the number of subdirectories under the directory
4: File owner
5: The group to which the file belongs
6: file size
7, 8, 9: The last time the file was modified
10: filename
command:
chgrp(change group): Change the group to which files and directories belong, the format is chgrp[group name][file name]
groupadd: add a user group
chown(change owner): Change the left and right of the file, the format is "chown[-R] account file name" or "chown[-R] account name: group name file name" (-R cascade change)
useradd: add a user
chmod(change mode): Change the user's read, write and execute permissions on files/directories, format: chmod[-R] xyz file name (xyz is a number)
umask: used to change the default permissions of the file, format: umask xxx (3 x for numbers)
(Note: To create a common file, there is no executable permission by default, only rw permission, 666)
(Note: When creating a directory, all permissions can be opened by default, 777)
The meaning of the umask value is the permissions that need to be subtracted from the default values in the above two rules