Inode structure and soft links and hard links

First look at block (concept of block), block is the smallest unit of file access, usually 8 sectors is a block, and each sector size is 512 bytes is 0.5K, so the size of a block is 8*0.5k=4k.

The system uses Inode to identify files

You can use the command stat to view inode information for a file, such as stat client.c

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You can see that the file information except for the filename is in the Inode

Therefore, the inode is the information that holds the file, called the index node

Command:

Stat file name//view inode information for a file

Df-i//View the total number of inode and quantity used for the hard disk partition

Ls-i filename//view inode number of the file

Df-h//block

A file consists of two parts: one is its meta information and the other is the file data

The file data is placed on the sector, but each time the operating system reads the data in blocks as the smallest unit

File meta information is stored in an area called Inode

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Hard link: Two or more files have the same inode number, assuming that two files A and b,a and B have the same inode number, opening either A and B essentially opens a file, and the other file changes for one of them. But deleting one of them does not affect another file.

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Create a hard-link ln source file destination file (the number of links in the inode struct is added 1)

Soft link: or fake A and b two files, and their two inode number is different, the content of a file is the path of B, that is, open any one of the files will open file B, called a is B soft link.

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Create a soft link ln-s source file destination file

Inode structure and soft links and hard links