hardlink

Consider only file content, not attributes, when determining whether two files are equal. Same as -pot.

The size of the read(2) or sendfile(2) buffer used when comparing file contents. The size argument may be followed by the multiplicative suffixes KiB, MiB, etc. The "iB" is optional, e.g., "K" has the same meaning as "KiB". The default is 8KiB for memcmp method and 1MiB for the other methods. The only memcmp method uses process memory for the buffer, other methods use zero-copy way and I/O operation is done in the kernel. The size may be altered on the fly to fit a number of cached content checksums.

Only try to link files with the same directory name. The top-level directory (as specified on the hardlink command line) is ignored. For example, hardlink --respect-dir /foo /bar will link /foo/some/file with /bar/some/file, but not /bar/other/file. If combined with --respect-name, then entire paths (except the top-level directory) are compared.

Only try to link files with the same (base)name. It’s strongly recommended to use long options rather than -f which is interpreted in a different way by other hardlink implementations.

Keep files found in the earliest specified top-level directory if there are multiple identical files in different trees. For example, hardlink foo/ bar/ will link files in bar/ to equal files in the foo/ directory.

A regular expression to include files. If the option --exclude has been given, this option re-includes files which would otherwise be excluded. If the option is used without --exclude, only files matched by the pattern are included.

Among equal files, keep the file with the highest link count.

Among equal files, keep the file with the lowest link count.

Do not act, just print what would happen.

Don’t link anything, but list the absolute path of every duplicate file, one per line, preceded by a unique 16-byte discriminator and a tab.

Separate lines with a NUL instead of a newline in -l mode.

Link and compare files even if their owner information (user and group) differs. Results may be unpredictable.

Among equal files, keep the oldest file (least recent modification time). By default, the newest file is kept. If --maximize or --minimize is specified, the link count has a higher precedence than the time of modification.

Link and compare files even if their mode is different. Results may be slightly unpredictable.

Quiet mode, don’t print anything.

The size of the cache for content checksums. All non-memcmp methods calculate checksum for each file content block (see --io-size), these checksums are cached for the next comparison. The size is important for large files or a large sets of files of the same size. The default is 10MiB.

The minimum size to consider. By default this is 1, so empty files will not be linked. The size argument may be followed by the multiplicative suffixes KiB (=1024), MiB (=1024*1024), and so on for GiB, TiB, PiB, EiB, ZiB and YiB (the "iB" is optional, e.g., "K" has the same meaning as "KiB").

The maximum size to consider. By default this is 0 and 0 has the special meaning of unlimited. The size argument may be followed by the multiplicative suffixes KiB (=1024), MiB (=1024*1024), and so on for GiB, TiB, PiB, EiB, ZiB and YiB (the "iB" is optional, e.g., "K" has the same meaning as "KiB").

Link and compare files even if their time of modification is different. This is usually a good choice.

Verbose output, explain to the user what is being done. If specified once, every hardlinked file is displayed. If specified twice, it also shows every comparison.

A regular expression that excludes files from being compared and linked. This option can be used multiple times.

A regular expression that excludes entire directories from being compared and linked. This option can also be used multiple times.

Do not traverse directories on different filesystems (remain within the same filesystem).

Only try to link files with the same extended attributes.

Set the file content comparison method. The currently supported methods are sha256, sha1, crc32c and memcmp. The default is sha256, or memcmp if Linux Crypto API is not available. The methods based on checksums are implemented in zero-copy way, in this case file contents are not copied to the userspace and all calculation is done in kernel.

Create copy-on-write clones (aka reflinks) rather than hardlinks. The reflinked files share only on-disk data, but the file mode and owner can be different. It’s recommended to use it with --ignore-owner and --ignore-mode options. This option implies --skip-reflinks to ignore already cloned files. The optional argument when can be never, always, or auto. If the when argument is omitted, it defaults to auto, in this case, hardlink checks filesystem type and uses reflinks on BTRFS and XFS only, and fallback to hardlinks when creating reflink is impossible. The argument always disables filesystem

Ignore already cloned files. This option may be used without --reflink when creating classic hardlinks.

Display help text and exit.

Display version and exit.