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.TH SUM 1
.SH NAME
sum, md5sum, sha1sum \- sum and count blocks in a file
.SH SYNOPSIS
.B sum
[
.B -5r
]
[
.I file ...
]
.PP
.B md5sum
[
.I file ...
]
.PP
.B sha1sum
[
.B -2
.I bits
] [
.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
.IR file s
are given,
the standard input is
summed.
Other summing algorithms are available.
The options are
.TF -r
.PD
.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
.I Md5sum
computes the 32 hex digit RSA Data Security, Inc. MD5 Message-Digest Algorithm
described in RFC1321.
.PP
.I Sha1sum
computes the 40 hex digit National Institute of Standards and Technology
(NIST)
SHA1 secure hash algorithm
described in FIPS PUB 180-1,
by default.
Given the
.L 2
option,
it instead computes the
.IR bits -bit
NIST SHA2 secure hash algorithm
described in FIPS PUB 180-2
and prints the hash in hex.
Currently supported values of
.I bits
are
224,
256,
384,
and
512.
.SH SOURCE
.B /sys/src/cmd/sum.c
.br
.B /sys/src/cmd/md5sum.c
.br
.B /sys/src/cmd/sha1sum.c
.SH "SEE ALSO"
.IR cmp (1),
.IR wc (1),
.IR sechash (2)
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