Linux link command

a grammar

ln -s [source file] [destination file]

Command English meaning: link

Function description: Generate link file

Options: -s create soft link

 

Two hard link features

 

It is fine to delete either the original file or the hard link file.

 

Three hard links in practice

1. [root@localhost ~]# cd test
2. [root@localhost test]# ls
3. bcd
4. [root@localhost test]# ln bcd abc.hard
5. [root@localhost test]# ll
6. total 0
7. -rw-r--r--.2 root root 0Jul1219:31 abc.hard
8. -rw-r--r--.2 root root 0Jul1219:31 bcd
9. [root@localhost test]# vi bcd
10. [root@localhost test]# cat abc.hard
11. qwer
12. [root@localhost test]# echo "dfd">> abc.hard
13. [root@localhost test]# cat bcd
14. qwer
15. dfd
16. [root@localhost test]# ls -i
17. 67170460 abc.hard 67170460 bcd
18. [root@localhost test]# rm bcd
19. rm: remove regular file ?.cd?. y
20. [root@localhost test]# cat abc.hard
21. qwer
22. dfd
23. [root@localhost test]# ll -i
24. total 4
25. 67170460-rw-r--r--.1 root root 10Jul1220:39 abc.hard

 Four soft link features

 

1. Delete the original file, the soft link file cannot be used.

2. Although the permission of the soft link file is 777, the real permission is still determined by the original file.

3. When creating a soft link, if the original file and the target file are in the same directory, there is no need to write the absolute path, otherwise the original file and the target file must write the absolute path. So the original file must write the absolute path.

Five actual combat

1. [root@localhost test]# ls
2. abc
3. [root@localhost test]# ln -s abc abc.soft
4. [root@localhost test]# ll
5. total 0
6. -rw-r--r--.1 root root 0Jul1220:42 abc
7. lrwxrwxrwx.1 root root 3Jul1220:55 abc.soft -> abc
8. [root@localhost test]#in abc abc.hard
9. -bash: syntax error near unexpected token `in'
10. [root@localhost test]# ln abc abc.hard
11. [root@localhost test]# ll
12. total 0
13. -rw-r--r--. 2 root root 0 Jul 12 20:42 abc
14. -rw-r--r--. 2 root root 0 Jul 12 20:42 abc.hard
15. lrwxrwxrwx. 1 root root 3 Jul 12 20:55 abc.soft -> abc
16. [root@localhost test]# ls -i
17. 67170460 abc 67170460 abc.hard 67170462 abc.soft
18. [root@localhost test]# echo 111 >>abc
19. [root@localhost test]# cat abc.soft
20. 111
21. [root@localhost test]# cat abc.hard
22. 111
23. [root@localhost test]# echo 222 >> abc.soft
24. [root@localhost test]# cat abc
25. 111
26. 222
27. [root@localhost test]# cat abc.soft
28. 111
29. 222
30. [root@localhost test]# rm -rf abc
31. [root@localhost test]# ll
32. total 4
33. -rw-r--r--. 1 root root 8 Jul 12 20:59 abc.hard
34. lrwxrwxrwx. 1 root root 3 Jul 12 20:55 abc.soft -> abc
35. [root@localhost test]# cat abc.hard
36. 111
37. 222
38. [root@localhost test]# rm -rf abc.soft
39. [root@localhost test]# ll
40. total 4
41. -rw-r--r--. 1 root root 8 Jul 12 20:59 abc.hard
42. [root@localhost test]# touch abc
43. [root@localhost test]# ln -s abc.soft
44. [root@localhost test]# ls
45. abc abc.hard abc.soft
46. [root@localhost test]# ll -i
47. total 4
48. 67170462 -rw-r--r--. 1 root root 0 Jul 12 21:01 abc
49. 67170460 -rw-r--r--. 1 root root 8 Jul 12 20:59 abc.hard
50. 67170463 lrwxrwxrwx. 1 root root 8 Jul 12 21:01 abc.soft -> abc.soft
51. [root@localhost test]# rm -rf *
52. [root@localhost test]# ll
53. total 0
54. [root@localhost test]# touch abc
55. [root@localhost test]# ln -s abc abc.soft
56. [root@localhost test]# ll
57. total 0
58. -rw-r--r--. 1 root root 0 Jul 12 21:05 abc
59. lrwxrwxrwx. 1 root root 3 Jul 12 21:05 abc.soft -> abc
60. [root@localhost test]# ln -s abc /tmp/ab.soft
61. [root@localhost test]# ll /tmp
62. total 0
63. lrwxrwxrwx. 1 root root 3 Jul 12 21:06 ab.soft -> abc
64. drwxr-xr-x. 3 root root 16 Jul 12 19:33 japan
65. [root@localhost test]# ll /tmp
66. total 0
67. lrwxrwxrwx. 1 root root 3 Jul 12 21:06 ab.soft -> abc
68. drwxr-xr-x. 3 root root 16 Jul 12 19:33 japan
69. [root@localhost test]# rm -rf /tmp/ab.soft
70. [root@localhost test]# ln -s /root/test/abc /tmp/ab.soft
71. [root@localhost test]# ll /tmp
72. total 0
73. lrwxrwxrwx. 1 root root 14 Jul 12 21:08 ab.soft -> /root/test/abc
74. drwxr-xr-x. 3 root root 16 Jul 12 19:33 japan

Six hard link and soft link file access diagram