In Linux/Unix systems, the same file can have multiple copies with different names, termed hardlinks. This provides convenience of modifying all the copies by modifying any copy. Today, I will introduce how to find all the hardlinks for a file.

How many copies does a file have?

One can find this information by using the following command:

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ls -l sample-file.txt
# output
# -rwxrw-r--. 2 user hacker 3351 Oct 23 11:11 sample-file.txt

The above output indicates that the file sample-file.txt has two copies: the second field is ‘2’ (if it was 1, then this file would be the only copy).

Find all the copies in the system

To find all copies for this file, we have two options, as follows:

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# option 1:
sudo find / -inum 656361
# option 2:
sudo find / -samefile sample-file.txt

For the above option 1, I used inode number 656361, which is the unique number for each file in a system; actually all file copies/hardlinks share the same inode number.

To find the inode number for a file, one can use the following command:

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ls -i sample-file.txt
# output
# 656361 sample-file.txt

If one doesn’t want to search the entire system but a folder, the path ‘/’ can be replaced with the folder path in the above methods.

I hope that this introduction helps. Happy programming 😃.

References

1. inode introduction: http://teaching.idallen.com/dat2330/04f/notes/links_and_inodes.html

Last modified on 2018-10-25