V4/man/man1/sum.1

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.th SUM I 3/15/72
.sh NAME
sum  \*-  sum file
.sh SYNOPSIS
.bd sum
name ...
.sh DESCRIPTION
.it Sum
sums the contents of the bytes (mod 2^16) of
one or more files and prints the answer in octal.
A separate sum is printed for each file specified,
along with the number of whole or partial
512-byte blocks read.
.s3
In practice,
.it sum
is often used to verify that
all of a special file can be read without error.
.sh BUGS