dpkg/utils/md5sum.1

.\" Hey, Emacs!  This is an -*- nroff -*- source file.
.TH MD5SUM 1 "29th November 1995" "Lankester et al" "Debian GNU/Linux"
.SH NAME
md5sum \- generates or checks MD5 message digests

.SH SYNOPSIS
.B md5sum
[-bv] [-c [file]] | [file...]

.SH DESCRIPTION
.B md5sum
generates or checks MD5 checksums. The algorithm to generate the
checksum is reasonably fast and strong enough for most cases. Exact
specification of the algorithm is in
.I RFC 1321.

Normally
.B md5sum
generates checksums of all files given to it as a parameter and prints
the checksums followed by the filenames. If, however,
.B -c
is specified, only one filename parameter is allowed. This file should
contain checksums and filenames to which these checksums refer to, and
the files listed in that file are checked against the checksums listed
there. See option
.B -c
for more information.

.SS OPTIONS
.TP
.B -b
Use binary mode. In unix environment, only difference between this and
the normal mode is an asterix preceding the filename in the output.
.TP
.B -c
Check md5sum of all files listed in
.I file
against the checksum listed in the same file. The actual format of that
file is the same as output of
.B md5sum.
That is, each line in the file describes a file. A line looks like:

.B <MD5 checksum>  <filename>

So, for example, if a file was created and its message digest calculated
like so:

.B echo foo > md5-test-file; md5sum md5-test-file

.B md5sum
would report:

.B d3b07384d113edec49eaa6238ad5ff00\  md5-test-file

.TP
.B -v
Be more verbose. Print filenames when checking (with -c).

.SH BUGS
The related MD4 message digest algorithm was broken in October 1995.
MD5 isn't looking as secure as it used to.

This manpage is not quite accurate and has formatting inconsistent
with other manpages.

.B md5sum
does not accept standard options like
.BR --help .

.SH AUTHOR

.B md5sum
was originally written by Branko Lankester, and modified afterwards by
Colin Plumb and Ian Jackson (ijackson@gnu.ai.mit.edu). Manual page was
added by Juho Vuori (javuori@cc.helsinki.fi)