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.TH SUM 1
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.SH NAME
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sum, md5sum, sha1sum \- sum and count blocks in a file
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.SH SYNOPSIS
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.B sum
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[
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.B -5r
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]
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[
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.I file ...
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]
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.PP
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.B md5sum
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[
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.I file ...
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]
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.PP
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.B sha1sum
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[
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.B -2
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.I bits
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] [
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.I file ...
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]
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.SH DESCRIPTION
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By default,
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.I sum
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calculates and prints a 32-bit hexadecimal checksum,
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a byte count,
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and the name of
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each
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.IR file .
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The checksum is also a function of the input length.
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If no
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.IR file s
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are given,
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the standard input is
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summed.
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Other summing algorithms are available.
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The options are
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.TF -r
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.PD
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.TP
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.B -r
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Sum with the algorithm of System V's
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.B "sum -r"
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and print the length (in 1K blocks) of the input.
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.TP
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.B -5
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Sum with System V's default algorithm
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and print the length (in 512-byte blocks) of the input.
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.PP
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.I Sum
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is typically used to look for bad spots,
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to validate a file communicated over
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some transmission line or
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as a quick way to determine if two files on different machines might be the same.
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.PP
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.I Md5sum
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computes the 32 hex digit RSA Data Security, Inc. MD5 Message-Digest Algorithm
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described in RFC1321.
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.PP
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.I Sha1sum
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computes the 40 hex digit National Institute of Standards and Technology
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(NIST)
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SHA1 secure hash algorithm
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described in FIPS PUB 180-1,
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by default.
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Given the
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.L 2
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option,
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it instead computes the
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.IR bits -bit
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NIST SHA2 secure hash algorithm
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described in FIPS PUB 180-2
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and prints the hash in hex.
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Currently supported values of
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.I bits
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are
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224,
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256,
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384,
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and
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512.
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.SH SOURCE
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.B /sys/src/cmd/sum.c
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.br
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.B /sys/src/cmd/md5sum.c
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.br
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.B /sys/src/cmd/sha1sum.c
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.SH "SEE ALSO"
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.IR cmp (1),
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.IR wc (1),
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.IR sechash (2)