Linux commands: ln command

Source: Internet
Author: User

ln command

Function description

The ln command is used to create links between files or directories.

There are two kinds of links under Linux, one is hard link, the other is symbolic link (symbolic link is often called soft link), the default is to use the LN command to create a hard link.

    • hard link

      refers to linking through the inode of a file. In a Linux file system, all types of files saved on disk are assigned a number, which

Number is called the inode number (Inode Index). Multiple files pointing to the same inode are allowed in the Linux system, which is called hard links. The purpose of a hard link is to allow a file to have multiple valid path names so that users can establish hard links to important files to prevent accidental deletions. Because there is more than one link to the inode of the file, deleting only one link does not affect the inode itself and other links, only if the last link is deleted, the file's data block and the directory's link will be released, that is, the file will be really deleted at this time.

    • Symbolic Links

Also called a soft link, a soft link is similar to a shortcut to Windows, so a soft link is a symbolic connection that points to a real file or directory location.

Use the following

Hard Link ln File link

Soft link ln-s Item link Here the item can be a file or it can be a directory

Command parameters

Options Meaning
-F If there is a file with the same link name in the target location, the file will be deleted
-S Make a soft link
-D Allow system administrators to hard-link their own directories
-B Back up files that will be overwritten or deleted at link time

Example

Hard-Link a file without parameters

[[email  protected] shell]# ln test.sh htest.sh                           #对源文件test. SH Create a hard link

[Email protected] shell]# ls-li #可以看到二个文件inode号相同

Total Dosage 8

68033834 -rw-r--r--. 2 root root 4 November 16:47 htest.sh

68033834 -rw-r--r--. 2 root root 4 November 16:47 test.sh

[[Email protected] shell]# ln htest.sh/tmp/ #链接到另一个目录, the target can not write the file name

[Email protected] shell]# ls-li/tmp/ #相同名称的硬链接, the inode number is the same

Total Dosage 32

68033834 -rw-r--r--. 4 root root 4 November 16:47 htest.sh

101282617-RW-------. 1 root root 26843 November 15:58 yum_save_tx.2016.r6hacv.yumtx

[Email protected] shell]#



Use the-b parameter to back up the link first

[[email protected] shell]# ln-b htest.sh test.sh #-b hard link before backup

[[email protected] shell]# ls-li #以 ~ The end is the backup file

Total Dosage 12

68033834-rw-r--r--. 4 root root 4 November 16:47 htest.sh

68033834-rw-r--r--. 4 root root 4 November 16:47 test.sh

68033834-rw-r--r--. 4 root root 4 November 16:47 test.sh~

- S a soft link that links the/etcinittab file symbol to the/opt

[email protected] ~]# ln-s/etc/inittab/opt

[Email protected] ~]# ls-li/opt/inittab #下面是软链接的显示 with different inode numbers

26186 lrwxrwxrwx. 1 root root 12 November 18:02 /opt/inittab-/etc/inittab

[Email protected] ~]# Ls-li/etc/inittab

34140601 -rw-r--r--. 1 root root 511 March 6 2015/etc/inittab

This article is from the "Zhao Dongwei blog" blog, make sure to keep this source http://zhaodongwei.blog.51cto.com/4233742/1871880

Linux commands: ln command

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