rdfind

What rdfind is

rdfind is a free command-line tool that finds duplicate files by comparing their contents rather than relying on filenames. It searches supplied directories recursively, including comparisons within or across directories, and can help compress backup directories. Matching uses file size, the first and last bytes, checksums, and inode and device identity handling. Checksum choices include MD5, SHA-1, SHA-256, SHA-512, and xxh128, with SHA-1 as the default. By default, rdfind writes a results file and leaves files unchanged. Options can delete duplicates or replace them with symbolic or hard links, while a dry run previews what an enabled action would do. Other options can ignore empty files or set minimum and maximum file sizes. The tool runs on Linux, macOS, and Windows: Linux distributions commonly provide packages, Mac users can install through MacPorts, and Windows users may use Cygwin. The manual cautions that changing directories during a run can make rdfind brittle and warns that deletion or linking can expose it to symlink attacks. It does not handle file ownership or permissions, so it is not recommended across directories with several owners.