98 lines
3.2 KiB
Groff
98 lines
3.2 KiB
Groff
.\" $NetBSD: same.1,v 1.2 2006/08/04 22:46:27 rillig Exp $
|
|
.Dd July 14, 2004
|
|
.Dt SAME 1
|
|
.Sh NAME
|
|
.Nm same
|
|
.Nd link identical files to save disk space
|
|
.Sh SYNOPSIS
|
|
.Nm
|
|
.Fl HVcdhnstuvz
|
|
.Sh DESCRIPTION
|
|
.Nm
|
|
takes a list of files (e.g. the output of find . -type f) on stdin.
|
|
Each of the files is compared against each of the others.
|
|
Whenever two files are found that match exactly, the two files are
|
|
linked (soft or hard) together.
|
|
.Ss Goal
|
|
The goal of this program is to conserve disk space when you have
|
|
several different trees of large projects on your disk.
|
|
By creating hardlinks or softlinks between the files that are the same,
|
|
you can save lots of disk space.
|
|
For example, two different versions of the Linux kernel only differ in a
|
|
small number of files.
|
|
By running this program you only need to store the contents of those
|
|
files once.
|
|
This is especially useful if you have different versions of complete
|
|
trees lying around.
|
|
.Ss Implementation
|
|
The filesize of every file is used as an indication of wether two
|
|
files can be the same. Whenever the filesizes match, the hashes of
|
|
these two files are compared. Whenever these match, the file
|
|
contents are compared. For every matching pair one of the two
|
|
files is replaced by a hard link to the other file.
|
|
With the -s option a softlink is used.
|
|
.Pp
|
|
To allow you to do this incrementally, the "rm" is done on the file
|
|
with the least links. This allows you to "merge" a new tree with
|
|
several trees that have already been processed. The new tree has
|
|
link count 1, while the old tree has a higher link count for those
|
|
files that are likely candidates for linkage.
|
|
.Pp
|
|
The current implementation keeps the "first" incantation of a file,
|
|
and replaces further occurrances of the same file. This is
|
|
significant when using softlinks.
|
|
.Ss Options
|
|
.Bl -tag -width xxxxxx
|
|
.It Fl H Ar n , Fl -hashstart Ar n
|
|
Start at hash value
|
|
.Ar n
|
|
instead of 0.
|
|
.It Fl V , Fl -version
|
|
Print the version of the program and exit.
|
|
.It Fl c Ar file , Fl -cache Ar file
|
|
Keep a cache between runs in file
|
|
.Ar file .
|
|
.It Fl d , Fl -debug
|
|
Output some debug messages.
|
|
.It Fl h , Fl -help
|
|
Output this page and exit successfully.
|
|
.It Fl n , Fl -dryrun
|
|
Only simulate.
|
|
.It Fl s , Fl -softlinks
|
|
Create soft links instead of hard links.
|
|
.It Fl u , Fl -user
|
|
Don't relink files owned by another user.
|
|
.It Fl v , Fl -verbose
|
|
Output verbose messages.
|
|
.It Fl z , Fl -nullfiles
|
|
Link empty files, too.
|
|
By default, only non-empty files are linked.
|
|
.El
|
|
.Sh EXIT STATUS
|
|
Zero on success, non-zero on failure.
|
|
.Sh EXAMPLES
|
|
.Bd -literal
|
|
find . -type f -print | same
|
|
.Ed
|
|
.Sh SEE ALSO
|
|
.Xr find 1
|
|
.Sh AUTHORS
|
|
.An "Roger E. Wolff" Aq R.E.Wolff@BitWizard.nl ,
|
|
.An "Geert Uytterhoeven" Aq geert@linux-m68k.org ,
|
|
.An "Roland Illig" Aq roland.illig@gmx.de .
|
|
.Sh CAVEATS
|
|
.Bl -bullet
|
|
.It
|
|
If your editor does not move the original aside before writing a
|
|
new copy, you will change the file in ALL incarnations when
|
|
editing a file.
|
|
Patch works just fine: it moves the original aside before creating a new
|
|
copy.
|
|
I'm confident that I could learn Emacs to do it this way too.
|
|
I'm too lazy to figure it out, so if you happen to know an easy way how
|
|
to do this, please Email me at
|
|
.Aq R.E.Wolff@BitWizard.nl .
|
|
.It
|
|
There is a 1024 (BUFSIZE) character limit to pathnames when using
|
|
symlinks.
|
|
.El
|