How to Locate Duplicate Files on Linux Using Inodes and Simple Scripts

When a computer stores many files, duplicate copies can waste disk space and slow down the system. On Linux, files that share the same inode value are essentially the same file, even if they have different names or locations.

Understanding inodes and hard links

An inode is a data structure that records all metadata of a file except its name and content. If two or more files have identical inode numbers, they are hard links to the same underlying data. Soft links (symbolic links) have their own inode and merely point to a target file.

Listing files with inode numbers

Use ls -i to display inode numbers, then sort them numerically to spot duplicates:

$ ls -i | sort -n | more
...
788000 myfile    <==
788000 mytwin    <==
801865 Name_Labels.pdf
...

The first column shows the inode; identical numbers indicate duplicate files.

Finding hard‑linked copies of a specific file

The find command with the -samefile option quickly lists all hard‑linked copies of a given file:

$ find . -samefile myfile
./myfile
./save/mycopy
./mytwin

These paths all share the same inode, confirming they are duplicates.

Bash script to automatically detect duplicate inodes

#!/bin/bash
# searches for files sharing inodes
prev=""
# list files by inode
ls -i | sort -n > /tmp/$0
while read line; do
    inode=$(echo $line | awk '{print $1}')
    if [ "$inode" == "$prev" ]; then
        grep $inode /tmp/$0
    fi
    prev=$inode
done < /tmp/$0
# clean up
rm /tmp/$0

Running the script prints inode numbers followed by the filenames that share them, e.g.:

$ ./findHardLinks
788000 myfile
788000 mytwin

Searching the entire filesystem by inode

You can also locate every file with a given inode using find -inum and suppress permission errors by redirecting them to /dev/null:

$ find / -inum 788000 -ls 2> /dev/null
788000 4 -rw-r--r-- 4 liangxu liangxu 228 Apr 12 19:37 /tmp/mycopy
788000 4 -rw-r--r-- 4 liangxu liangxu 228 Apr 12 19:37 /home/liangxu/myfile
...

This approach helps you identify and remove redundant files, freeing up valuable disk space.