HARDLINK(1) User Commands HARDLINK(1)
NAME
hardlink - link multiple copies of a file
SYNOPSIS
hardlink [options] [directory|file]...
DESCRIPTION
hardlink is a tool which replaces copies of a file with hardlinks,
therefore saving space.
OPTIONS
-h, --help
print quick usage details to the screen.
-v, --verbose
More verbose output. If specified once, every hardlinked file is
displayed, if specified twice, it also shows every comparison.
-q, --quiet
Quiet mode, don’t print anything.
-n, --dry-run
Do not act, just print what would happen.
-f, --respect-name
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.
-p, --ignore-mode
Link and compare files even if their mode is different. Results may
be slightly unpredictable.
-o, --ignore-owner
Link and compare files even if their owner information (user and
group) differs. Results may be unpredictable.
-t, --ignore-time
Link and compare files even if their time of modification is
different. This is usually a good choice.
-X, --respect-xattrs
Only try to link files with the same extended attributes.
-m, --maximize
Among equal files, keep the file with the highest link count.
-M, --minimize
Among equal files, keep the file with the lowest link count.
-O, --keep-oldest
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.
-x, --exclude regex
A regular expression which excludes files from being compared and
linked.
-i, --include regex
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.
-s, --minimum-size size
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").
-S, --buffer-size size
The size of read buffer used when comparing file contents (default:
8KiB). This costs some additional memory but potentially reduces
the amount of seek operations and therefore improve performance,
especially with mechanic disk drives. Optional factor suffixes are
supported, like with the -s option. This is mostly efficient with
other filters (i.e. with -f or -X) and can be less efficient with
-top options.
ARGUMENTS
hardlink takes one or more directories which will be searched for files
to be linked.
BUGS
The original hardlink implementation uses the option -f to force
hardlinks creation between filesystem. This very rarely usable feature
is no more supported by the current hardlink.
hardlink assumes that the trees it operates on do not change during
operation. If a tree does change, the result is undefined and
potentially dangerous. For example, if a regular file is replaced by a
device, hardlink may start reading from the device. If a component of a
path is replaced by a symbolic link or file permissions change,
security may be compromised. Do not run hardlink on a changing tree or
on a tree controlled by another user.
AUTHOR
There are multiple hardlink implementations. The very first
implementation is from Jakub Jelinek for Fedora distribution, this
implementation has been used in util-linux between versions v2.34 to
v2.36. The current implementations is based on Debian version from
Julian Andres Klode.
REPORTING BUGS
For bug reports, use the issue tracker at
https://github.com/karelzak/util-linux/issues.
AVAILABILITY
The hardlink command is part of the util-linux package which can be
downloaded from Linux Kernel Archive
<https://www.kernel.org/pub/linux/utils/util-linux/>.
util-linux 2.37.2 2024-04-09 HARDLINK(1)
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