What is hard link and soft link in Linux?

A symbolic or soft link is an actual link to the original file, whereas a hard link is a mirror copy of the original file. If you delete the original file, the soft link has no value, because it points to a non-existent file. But in the case of hard link, it is entirely opposite.

A hard link is a file that points to the same underlying inode, as another file. In case you delete one file, it removes one link to the underlying inode. Whereas a symbolic link (also known as soft link) is a link to another filename in the filesystem.

You can check if a file is a symlink with [ -L file ] . Similarly, you can test if a file is a regular file with [ -f file ] , but in that case, the check is done after resolving symlinks. hardlinks are not a type of file, they are just different names for a file (of any type).

Perhaps the most useful application for hard links is to allow files, programs and scripts (i.e. short programs) to be easily accessed in a different directory from the original file or executable file (i.e., the ready-to-run version of a program).

A hard link is essentially a synced carbon copy of a file that refers directly to the inode of a file. Symbolic links on the other hand refer directly to the file which refers to the inode, a shortcut.

If you find two files with identical properties but are unsure if they are hard-linked, use the ls -i command to view the inode number. Files that are hard-linked together share the same inode number. The shared inode number is 2730074, meaning these files are identical data.

Most file systems that support hard links use reference counting. An integer value is stored with each physical data section. This integer represents the total number of hard links that have been created to point to the data. When a new link is created, this value is increased by one.

Use the ls -l command to check whether a given file is a symbolic link, and to find the file or directory that symbolic link point to. The first character “l”, indicates that the file is a symlink. The “->” symbol shows the file the symlink points to.

To view the symbolic links in a directory:

  1. Open a terminal and move to that directory.
  2. Type the command: ls -la. This shall long list all the files in the directory even if they are hidden.
  3. The files that start with l are your symbolic link files.

To create a hard links on a Linux or Unix-like system:

  1. Create hard link between sfile1file and link1file, run: ln sfile1file link1file.
  2. To make symbolic links instead of hard links, use: ln -s source link.
  3. To verify soft or hard links on Linux, run: ls -l source link.

16 окт. 2018 г.

To create a symbolic link is Linux use the ln command with the -s option. For more information about the ln command, visit the ln man page or type man ln in your terminal. If you have any questions or feedback, feel free to leave a comment.

Hard link is the exact replica of the actual file it is pointing to . Both the hard link and the linked file shares the same inode . If the source file is deleted ,the hard link still works and you will be able to access the file until the number of hard links to file isn’t 0(zero).

A symbolic link is a special type of file whose contents are a string that is the pathname of another file, the file to which the link refers. (The contents of a symbolic link can be read using readlink(2).) In other words, a symbolic link is a pointer to another name, and not to an underlying object.

Yes. They both take space as they both still have directory entries.

Each hard linked file is assigned the same Inode value as the original, therefore they reference the same physical file location. Hard links more flexible and remain linked even if the original or linked files are moved throughout the file system, although hard links are unable to cross different file systems.

A hard link will never point to a deleted file. A hard link is like a pointer to the actual file data. And the pointer is called “inode” in file system terminology. So, in other words, creating a hard link is creating another inode or a pointer to a file.

Like this post? Please share to your friends:
OS Today