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This article mainly introduces the Linux file system and some command example analysis, has a certain reference value, interested friends can refer to, I hope you can learn a lot after reading this article, the following let the editor with you to understand.

1. Disk partitions and file systems

1.1 hard disk Partition

A new hard disk cannot be used directly after it is installed on the computer and needs to be partitioned. Then the partition is formatted as a file system, so that the Linux system can store data and manage and maintain the corresponding files on the formatted partition. A hard disk partition on a Linux or UNIX system is equivalent to a logical disk on a Windows system.

1.2 Partition format description

Formatting a partition as a file system means that the partition of the disk is divided into many small units of equal size and numbered sequentially. These small units are called blocks, and the default block size for Linux is 4KB. On Linux systems, block is the smallest unit of data storage, and each block can store at most one file. If a file size is larger than 4KB, it will take up more than one block.

1.3I (inode) node

1.3.1 I node definition

An I node is a list of information related to a particular object, such as a file or directory. The I node is actually a data structure that stores basic information about a normal file, directory, or other file system object. The number of I nodes determines the maximum number of files that can be stored in this file system (partition), because none of the files and directories correspond to a unique I node, which is identified by the I node number (inode number, inodeno). In a typical UNIX or Linux file system, the I node takes up about 1% of the entire file system. The I node is similar to the bibliography.

1.3.2 I node structure

(1) inode-no is the I node number, and in a file system, each I node has a unique number.

(2) File type is a file type. For example, "-" is an ordinary file and d is a directory.

(3) permission is the permission. Use digital methods to record permissions to save space, such as 644.

(4) Link count is the number of hard connections (hard link)

(5) UID is the file owner ID

(6) GID is the group ID to which the file owner belongs.

(7) size is the file size

(8) Time stamp is a timestamp. Contains 3 times

The last time ① Access time (A time) accessed this file

② Modify time (M time) last time to edit this file

③ Chanage time (C time) refers to the time when the metadata in the I node (inode) changes relative to any column of the file.

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