ln command in linux

Question

I have a doubt regarding what are the differences when we make a new file using touch command and when we make a new hard-link to a file. It would be nice for me if you can explain me it in detail.

Answer 1

touch (with only a name as the argument) simply creates a new (empty) file. That file has no relation to any other file, it's stand-alone.

Creating a new hard link (using ln without the -s switch) will create a second directory entry for the same "file". This means that you now have two directory entries (each representing a name) that access the same content: if you append to one of them, then that change is represented in the other. Deleting one, will keep the other one alive (because deleting a "file" per default only deletes the directory entry. Only if that was the last one, will the "real" content be deleted).

Answer 2

'touch' creates a new file, while a hard link is just another name for the same file.

Try it with the following commands:

touch file1.txt
touch file2.txt
touch file3.txt
ln file3.txt file4.txt
echo "Hello world!" >> file1.txt
echo "Hello world!" >> file2.txt
echo "Hello world!" >> file3.txt
echo "Hello world!" >> file4.txt

Check the contents: file1.txt and file2.txt should both contain one line. file3.txt and file4.txt both contain two lines.

Answer 3

touch will create a brand new file while ln will link to an EXISTING file

Answer 4

man ln and man touch. These commands are not related in any way.

Links don't allocate a new inode, other entries do. You can find out the inode number for files using

 ls -i

(or ls -li etc).

To find a file with a given inode number:

 find -inum 98398

Inodes are unique only withing a filesystem Hardlinking is only possible within a single filesystem