man.postnix Miscellaneous man pages of Plan 9 related material

     SUM(1)                                                     SUM(1)

     NAME
          sum, md5sum - sum and count blocks in a file

     SYNOPSIS
          sum [ -5r ] [ file ... ]

          md5sum [ file ... ]

     DESCRIPTION
          By default, sum calculates and prints a 32-bit hexadecimal
          checksum, a byte count, and the name of each file. The
          checksum is also a function of the input length.  If no
          files are given, the standard input is summed.  Other sum-
          ming algorithms are available.  The options are

          -r   Sum with the algorithm of System V's sum -r and print
               the length (in 1K blocks) of the input.

          -5   Sum with System V's default algorithm and print the
               length (in 512-byte blocks) of the input.

          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.

          Md5sum computes the 32 hex digit RSA Data Security, Inc. MD5
          Message-Digest Algorithm described in RFC1321.  If no files
          are given, the standard input is summed.

     SOURCE
          /sys/src/cmd/sum.c
          /sys/src/cmd/md5sum.l

     SEE ALSO
          cmp(1), wc(1)

     Page 1                       Plan 9            (printed 10/28/25)