Why does the 10.x/11.x cksum command produce a different checksum than the 9.x cksum command? Updated: 04/05/01

The 9.x cksum was defective - it did not correctly implement the POSIX
spec. That is understandable, because the POSIX cksum spec does not
supply a test suite to easily verify an implementation is correct.

The 10.x/11.x cksum is correct. Unfortunately that means it can not
match 9.x cksum.

Another implementation that did not match POSIX spec was in AIX 3.*; I
haven't checked AIX 4.* or Solaris.

Other good implementations (they give the same answer as 10.x/11.x
- GNU cksum
- Solaris 7/8
- HP Software Distributor swpackage program, on both 9.x and 10.x

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