.TH "FINDDUP" 1 "Mar 2010" "Francois Fleuret" "User Commands"

\" This man page was written by Francois Fleuret <francois@fleuret.org>
\" and is distributed under a Creative Commons Attribution-Share Alike
\" 3.0 License.

.SH "NAME"

finddup \- Find files common to two directories (or not)

.SH "SYNOPSIS"

\fBfinddup\fP [OPTION]... DIR1 [[and:|not:]DIR2]

.SH "DESCRIPTION"

With a single directory argument, \fBfinddup\fP prints the duplicated
files found in it.

With two directories, it prints either the files common to both DIR1
and DIR2 or, with the `not:' prefix, the ones present in DIR1 and not
in DIR2. The and: prefix is assumed by default and necessary only if
you have a directory name starting with `not:'.

This command compares files by first comparing their sizes, hence goes
reasonably fast.

When looking for identical files, \fBfinddup\fP associates a group ID
to every content, and prints it along the file names. Use the \fB-g\fP
to switch it off.

Note that
.B finddup DIR
is virtually the same as
.B finddup -i DIR DIR

.SH "OPTIONS"
.TP
\fB-h\fR, \fB--help\fR
display help and exit
.TP
\fB-d\fR, \fB--ignore-dots\fR
ignore files and directories starting with a dot
.TP
\fB-0\fR, \fB--ignore-empty\fR
ignore empty files
.TP
\fB-c\fR, \fB--hide-matchings\fR
do not show which files from DIR2 corresponds to files from DIR1
(hence, show only the files from DIR1 which have an identical twin in
DIR2)
.TP
\fB-g\fR, \fB--no-group-ids\fR
do not show the file group IDs
.TP
\fB-p\fR, \fB--show-progress\fR
show progress information in stderr
.TP
\fB-r\fR, \fB--real-paths\fR
show the real path of the files
.TP
\fB-i\fR, \fB--same-inodes-are-different\fR
files with same inode are considered as different
.TP
\fB-m\fR, \fB--md5\fR
use MD5 hashing (if compiled with the option)

.SH "BUGS"

None known, probably many. Valgrind does not complain though.

The MD5 hashing is not satisfactory. It is computed for a file only if
the said file has to be read fully for a comparison (i.e. two files
match and we have to read them completely).

Hence, in practice lot of partial MD5s are computed, which costs a lot
of cpu and is useless. This often hurts more than it helps. The only
case when it should really be useful is when you have plenty of
different files of same size, and lot of similar ones, which does not
happen often.

Forcing the files to be read fully so that the MD5s are properly
computed is not okay neither, since it would fully read certain files,
even if we will never need their MD5s.

Anyway, it has to be compiled in with 'make WITH_MD5=yes', and even in
that case it will be off by default

.SH "WISH LIST"

The format of the output should definitely be improved. Not clear how.

Their could be some fancy option to link two instances of the command
running on different machines to reduce network disk accesses. Again,
this may not help much, for the reason given above.

.SH "EXAMPLES"

.B finddup -p0d blah

.fi
List duplicated files in directory ./blah/, show a progress bar,
ignore empty files, and ignore files and directories starting with a
dot.

.P
.B finddup sources not:/mnt/backup

.fi
List all files found in \fB./sources/\fR which do not have
content-matching equivalent in \fB/mnt/backup/\fR.

.P
.B finddup -g tralala cuicui

.fi
List groups of files with same content which exist both in
\fB./tralala/\fR and \fB./cuicui/\fR. Do not show group IDs, instead
write an empty lines between groups of files of same content.

.SH "AUTHOR"

Written by Francois Fleuret <francois@fleuret.org> and distributed
under the terms of the GNU General Public License version 3 as
published by the Free Software Foundation. This is free software: you
are free to change and redistribute it. There is NO WARRANTY, to the
extent permitted by law.