Unix Links ( Symbolic links)
Unix links, also known as a symlink or symbolic links, is a special type of file that points to another file or directory.
We will learn below topics in this article:
What is a link in Unix?
- A link in UNIX is a pointer to a file.
- Creating links is a kind of shortcut to access a file.
There are two types of links :
- Hard Link
- Soft Link or Symbolic Links
Hard link
- Both the original file and hard linked file have the same inode numbers, therefore they reference the same physical file location.
- If the original file is deleted , the link is not deleted, hard links are more flexible
- Are more efficient (in terms of access time) as compared to soft links.
- This can not be used to link a file on another file system, or to link directories
Syntax:
$ ln [original filename] [link name] Soft linkÂ
- The original file and the link have different inode numbers. Each soft linked file points to the original file
- When the original file is deleted, the link remains as an invalid link and will not behave correctly. It is called as hanging link
- Soft Link contains the path for original file, if original file is removed it impacts the link functionality
- This can be used to link file on a different file systemÂ
- Can be used to link directories
Syntax:
$ ln -s [original filename] [link name]
How to Use the ln Command to create Unix Links
ln command in Unix is used for creating links between files. By default, the ln command creates hard links.
To create a symbolic link, use the -s (–symbolic) option.
1. Create link to a file
SYNTAX: ln -s [OPTIONS] FILE LINK
If both the FILE and LINK are given, ln will create a link from the file specified as the first argument (FILE) to the file specified as the second argument (LINK).
If only one file is given as an argument or the second argument is a dot (.), ln will create a link to that file in the current working directory . The name of the symlink will be the same as the name of the file it points to.
on successful execution , no output is displayed but returns zero.
2. Creating Symlink To a File
To create a symbolic link to a given file use -s option:
SYNTAX: ln -s FILE symbolic_link
The symbolic_link parameter is optional. The ln command will create a new link in your current directory in case it is not mentioned.
The -> symbol shows the file the symlink points to.
3. Create Symlinks to a Directory
Directory name is used as the first parameter and the symlink as the second parameter.
SYNTAX: ln -s DIRECTORY LINK
Example:s
4. Overwriting Symlinks
If you try to create a symbolic link that already exists , the ln command will print an error message.
To overwrite the destination path of the symlink, use the -f (–force) option.
SYNTAX: ln -sf FILE LINK
5. Removing Symlinks
unlink or rm command is used to remove the links from file or directory.
SYNTAX:
unlink LINKNAME
or
rm LINKNAME