Linux Learning 12-linux file properties

Linux file properties

In Linux, for each file has the corresponding attributes, in the root user home directory of Linux in the new file A.txt as an example, enter a few characters in the A.txt

1. Use command Ls-ild a.txt to view file permissions, etc.

[Email protected] ~]# Ls-ild a.txt

1057689-rw-r--r--. 1 root root 8 Apr 9 19:42 a.txt

Description

First column: 1057689 inode number of the file

1th bit of the second column:-file type, common file types include

D: Folder

-: Normal file

L: Links (Windows-like shortcuts)

B: block device files (e.g. hard drives, optical drives, etc.)

P: Pipeline File

C: Character device files (e.g. serial devices such as cats)

S: Set of interface files/data interface files (e.g. a Mysql.sock file is generated when starting a MySQL server)

Second column 第2-10位: rw-r--r--file user, user group, other user other (others is the user except root (root has the highest privilege), the file owner, the file belongs to the user group all users) right

The third column:. Point indicates that the file is protected by SELinux and the selinux mechanism is turned on to indicate

Fourth column: 1 1 indicates the number of inode connections, that is, the number of hard links

Fifth column: root-owned users

Sixth column: root-owned user group

Seventh column: 8 file size, default in bytes

Eighth column: APR 9 19:42 Last modified (created)

Nineth column: A.txt file absolute path and name

1. Use the command stat a.txt to view file detail properties

[Email protected] ~]# stat a.txt

File: ' A.txt '

Size:8 blocks:8 IO block:4096 Regular file

device:802h/2050d inode:1057689 links:1

Access: (0644/-rw-r--r--) Uid: (0/root) Gid: (0/root)

access:2018-04-09 19:42:13.300081234 +0800

modify:2018-04-09 19:42:13.300081234 +0800

change:2018-04-09 19:42:13.361073559 +0800

Description

File: ' a.txt ' file name

Size:8 File Size

Total number of data blocks used by the Blocks:8 file

Io block:4096 io block size

Regular file type: General file

device:802h/2050d Device number

inode:1057689 inode Number

Links:1 Number of links

Access: Permissions for (0644/-rw-r--r--) files

UID: (0/root) GID: (0/root) file ownership of GID and UID

access:2018-04-09 19:42:13.300081234 +0800 Access time

modify:2018-04-09 19:42:13.300081234 +0800 Modification Time

change:2018-04-09 19:42:13.361073559 +0800 State modification Time

3, about these three kinds of time description

1> access times (access time abbreviated to ATIME)

2> Modified (Modify time abbreviated to Mtime)

3> State modification Time (change times abbreviated to CTime)

Atime: (Access Time), which shows when the data in the file was last accessed, such as the system

Process is used directly or indirectly through some commands and scripts. (Execute some executable file or script)

Mtime: (modifytime) modified the file content Mtime changed. The modified time, which shows the last time the contents of the file were modified, such as when editing with VI, will be changed. (i.e. the contents of block)

CTime: (changetime) modified the file attributes CTime changed. State modification, Time displays the attributes, that is, the permissions of the file, the owner, the group to which it belongs, and the time when the number of links has changed. Of course, when content changes, it changes (i.e. when the inode content changes and the block content changes)

Updates for Atime

[Email protected] ~]# stat a.txt

File: ' A.txt '

Size:8 blocks:8 IO block:4096 Regular file

device:802h/2050d inode:1057689 links:1

Access: (0644/-rw-r--r--) Uid: (0/root) Gid: (0/root)

access:2018-04-09 19:42:13.300081234 +0800

modify:2018-04-09 19:42:13.300081234 +0800

change:2018-04-09 19:42:13.361073559 +0800

[email protected] ~]# cat A.txt

Abcdefg

[Email protected] ~]# stat a.txt

File: ' A.txt '

Size:8 blocks:8 IO block:4096 Regular file

device:802h/2050d inode:1057689 links:1

Access: (0744/-rwxr--r--) Uid: (0/root) Gid: (0/root)

access:2018-04-09 19:49:36.626081357 +0800

modify:2018-04-09 19:42:13.300081234 +0800

change:2018-04-09 19:42:13.361073559 +0800

Mtime Update (Append the contents of the file, while modifying the content, the size of the file also changed, so its ctime also changed)

[Email protected] ~]# stat a.txt

File: ' A.txt '

Size:8 blocks:8 IO block:4096 Regular file

device:802h/2050d inode:1057689 links:1

Access: (0744/-rwxr--r--) Uid: (0/root) Gid: (0/root)

access:2018-04-09 19:49:36.626081357 +0800

modify:2018-04-09 19:42:13.300081234 +0800

change:2018-04-09 19:48:48.649078595 +0800

[Email protected] ~]# echo "Hello World" >>a.txt

[Email protected] ~]# stat a.txt

File: ' A.txt '

Size:20 blocks:8 IO block:4096 Regular file

device:802h/2050d inode:1057689 links:1

Access: (0744/-rwxr--r--) Uid: (0/root) Gid: (0/root)

access:2018-04-09 19:49:36.626081357 +0800

modify:2018-04-09 19:57:45.272068288 +0800

change:2018-04-09 19:57:45.272068288 +0800

Updates for CTime

[Email protected] ~]# stat a.txt

File: ' A.txt '

Size:8 blocks:8 IO block:4096 Regular file

device:802h/2050d inode:1057689 links:1

Access: (0644/-rw-r--r--) Uid: (0/root) Gid: (0/root)

access:2018-04-09 19:42:13.300081234 +0800

modify:2018-04-09 19:42:13.300081234 +0800

change:2018-04-09 19:42:13.361073559 +0800

[Email protected] ~]# chmod u+x a.txt

[Email protected] ~]# stat a.txt

File: ' A.txt '

Size:8 blocks:8 IO block:4096 Regular file

device:802h/2050d inode:1057689 links:1

Access: (0744/-rwxr--r--) Uid: (0/root) Gid: (0/root)

access:2018-04-09 19:42:13.300081234 +0800

modify:2018-04-09 19:42:13.300081234 +0800

change:2018-04-09 19:48:48.649078595 +0800

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Linux Learning 12-linux file properties