.\" Copyright (c) 2004 B. Luevelsmeyer
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.\" $Id: dupfind.1,v 1.5 2007/05/03 14:35:02 bernd Exp $
.Dd December 30, 2004
.Dt DUPFIND 1
.Os
.Sh NAME
.Nm dupfind
.Nd "find duplicate files"
.Sh SYNOPSIS
.Nm
.Op Fl cshdv0p
.Op Ar pathname ...
.Sh DESCRIPTION
.Nm
finds copies of files in the directory trees
.Ar pathname .
It distinguishes between hardlinked files, softlinked files, and actual
copies.
.Pp
The options control the output. Per default, nothing is output.
.Bl -tag -width ".Fl c"
.It Fl c
Write statistical summary at program exit.
.It Fl s
Report symbolic links.
.It Fl h
Report hard links.
.It Fl d
Report non-linked copies.
.It Fl v
Write debugging output. This is intended for development purposes.
.It Fl 0
Do not consider files of size 0 to be copies of each other.
.It Fl p
Write a progress indicator to stderr (currently searched directory).
.El
.Pp
The output, written to stdout, consists of one line per copy, each
containing the names and the size of 2 identical files. Lines starting
with ``=='' are hardlinks, those starting with ``||'' are actual copies,
and those starting with ``->'' are softlinks; the filenames and the
length (in bytes) are enclosed in ``><'' and separated with whitespace.
The output is intended to be easily parseable by other programs such as
.Xr awk 1 .
An example shellskript (generating HTML pages with awk) is part of the
source distribution.
.Pp
.Nm
works by searching the directory trees recursively; it stores the
filenames it encounters into a database along with the file lengths. If
it later encounters a file with the same length, it calculates a
checksum on both files (which is also stored in the database so it needs
to be calculated at most once per file). If the checksums match too,
then the files are compared directly. Usually only very few checksums
need to be calculated, and almost no files need to be compared.
.Sh ENVIRONMENT AND FILES
.Nm
uses two temporary
.Xr db 3
databases for its work. These databases will be created in the path
indicated by the
.Ev TMPDIR
environment variable. If the variable does not exist, the databases are
created in ``/tmp''. The databases are not deleted at program end if the
flag
.Fl v
is supplied on the command line. Their size is roughly proportional to
the number of files found in the directory trees.
.Sh EXAMPLES
To find hardlinks and copies in the directory tree starting at ``/home''
and output a summary, while storing the databases in the current
directory, use
.Pp
.Dl "env TMPDIR=. dupfind -hdc /home"
.Sh DIAGNOSTICS
Exit status is 0 on success, and not 0 if the program fails for any
reason. The error messages should be self-explanatory; database errors
will always abort the program immediately.
.Sh SEE ALSO
.Xr awk 1 ,
.Xr db 3
.Sh BUGS
.Nm
will occasionally miss some copies if the files are in active use.