1. Junior Level Linux Certification

2. Exam Objectives
Key Knowledge Areas
Create links.
Identify hard and/or softlinks.
Copying versus linking files.
Use links to support system administration tasks.
Objective 4: Devices, Linux Filesystems, Filesystem Hierarchy Standard
Create and change hard and symbolic links Weight: 2
Terms and Utilities
ln
2

3. Create and change hard and symbolic links
Disk file format
3

4. Create and change hard and symbolic links
inodes
4

5. Create and change hard and symbolic links
inodes
5

6. Hard link
hard link maintains the same permissions and access times of the original file
both have same inode number - simply appears to have different filename and/or location
6
Create and change hard and symbolic links
•Changes to either the original file or the link affect both.
•The two files have equal importance. But deleting either of files won’t affect the other.
•Hard link files appear to be regular files when examined and they function this way as
well
• Normal users can’t create hard links to directories.
• Also, hard links aren’t allowed to span file systems
To create a hard link, use the ln command
# ln stuff2 /home/angie/stuff
# ls –al
-rw-r--r-- 2 root root 89704 Aug 27 2000 stuff
-rw-r--r-- 2 root root 89704 Aug 27 2000 stuff2
Ex:

7. Create and change hard and symbolic links
Hard links
7

8. Symbolic link
Users can create symbolic links to directories, and symbolic links can span file systems.
8
Create and change hard and symbolic links
• Symbolic link maintains permissions separate from those of the original file.
• Deleting the original file won’t remove the symbolic link, but the link wont funtion.
To create a soft link, you use the ln command.
# ln –s stuff /home/angie/stuffEx:
Soft links can be identified by listing the details of a directory’s contents:
# ls –al
lrwxrwxrwx 1 angie angie 7 Mar 10 17:06 stuff -> /fun/stuff
Ex:

9. Create and change hard and symbolic links
Symbolic links
9

10. Create and change hard and symbolic links
Symbolic Links to Different File Systems
10

11. Create and change hard and symbolic links
Multiple Links to One File
11

12. Fim de sessão
12