Ls-l command

Ls-l the LL command can view the properties of a file in a long format.

The first part is the type of file, the main permission, the group permissions, other permissions, the second part of the number of hard links, the third part is the main, the fourth part of the group, the fifth part of the modified time, sixth part of the file name.

The types of files are divided into:

B-Block devices, C-character devices 、--Files, D-Directories, L-links,

Zero, NULL, and random devices, such as/dev below, are character devices

/dev/mapper The following logical volumes are mapped to connected devices

The above logical volume connected device/dev/dm-* is a block device

A lot of files and directories

I/O devices in Linux are divided into two categories: block devices and character devices

Character device: Provides a continuous stream of data that the application can read sequentially and does not normally support random access. Instead, such devices support reading and writing data by byte/character.

Block device: The application can randomly access the device data, and the program can determine where to read the data at its own discretion. A hard disk is a typical block device in which an application can address any location on a disk and read data from it.

Connections are divided into soft and hard links

For example: the use of ln-s to create a soft connection, the soft link to delete the source file after the linked file is not good, hard links can still be used, hard links occupy the inode and block, soft connections do not occupy.

Files are divided into Atime (access time), CTime (change times), Mtime (Modify)

Ls-l default display Mtime,ls-la can display atime, LS-LC can display CTime

Mtime is the time to modify the contents of a file, Atime is the time to access the file, CTime includes changing the file name, the file attributes.

Ls-l command