.TH SUM 1
.SH NAME
sum, md5sum \- sum and count blocks in a file
.SH SYNOPSIS
.B sum
[
.B -5r
]
[
.I file ...
]
.PP
.B md5sum
[
.I file ...
]
.SH DESCRIPTION
By default,
.I sum
calculates and prints a 32-bit hexadecimal checksum,
a byte count,
and the name of
each
.IR file .
The checksum is also a function of the input length.
If no files are given,
the standard input is
summed.
Other summing algorithms are available.
The options are
.TP
.B -r
Sum with the algorithm of System V's
.B "sum -r"
and print the length (in 1K blocks) of the input.
.TP
.B -5
Sum with System V's default algorithm
and print the length (in 512-byte blocks) of the input.
.PP
.I Sum
is typically used to look for bad spots,
to validate a file communicated over
some transmission line or
as a quick way to determine if two files on different machines might be the same.
.PP
.B Md5sum
computes the 32 hex digit RSA Data Security, Inc. MD5 Message-Digest Algorithm
described in RFC1321.
If no
.I files
are given,
the standard input is
summed.
.SH SOURCE
.B /sys/src/cmd/sum.c
.br
.B /sys/src/cmd/md5sum.l
.SH "SEE ALSO"
.IR cmp (1),
.IR wc (1)
