dce@mips.COM (David Elliott) (02/02/88)
Does anyone know why sum on System V-based systems produces
different results by default than sum on BSD-based systems?
I notice also that System V sum has a -r option for using an
alternate algorithm, which generates the same results as the
BSD sum.
--
David Elliott dce@mips.com or {ames,prls,pyramid,decwrl}!mips!dcegwyn@brl-smoke.ARPA (Doug Gwyn ) (02/08/88)
In article <1451@quacky.mips.COM> dce@mips.COM (David Elliott) writes: >Does anyone know why sum on System V-based systems produces >different results by default than sum on BSD-based systems? Because they evolved by different paths (but I bet you knew that). I think somebody decided that "sums the bytes in a file" should be taken literally. >I notice also that System V sum has a -r option for using an >alternate algorithm, which generates the same results as the >BSD sum. Yes, use that flavor for checksum purposes.
lvc@tut.cis.ohio-state.edu (Lawrence V. Cipriani) (02/09/88)
In article <7222@brl-smoke.ARPA> gwyn@brl.arpa (Doug Gwyn (VLD/VMB) <gwyn>) writes: >Yes, use that flavor for checksum purposes. (Doug was speaking of sum -r here) Though this is much better than just summing up the bytes, it hardly qualifies as a good checksum. It is easy to find different sequences of numbers that generate the same "sum -r" (if you know the algorithm). It is not a crc if that is what you are looking for. There were some crc codes floating around on Usenet once, but I don't have them now. -- oo Larry Cipriani, AT&T Networks Systems (by day) Ohio State University (by night) Domain: lvc@tut.cis.ohio-state.edu Path: ...!cbosgd!osu-cis!tut.cis.ohio-state.edu!lvc (yes its right)