bill@twg.bc.ca (Bill Irwin) (05/27/91)
I would like to know if there is a command under SCO XENIX 2.3.3 that will produce a checksum on a file, so that later, another checksum could be compared to the first; and if different, you would know that the file had been modified. Looking at the byte size of the file is a fairly good indicator if it has been modified, but changes can be made to files that leave the byte size the same. Ideally, the command would produce a checksum that could be stored in a file along with the checked file's name. Is there such a beast? -- Bill Irwin - The Westrheim Group - Vancouver, BC, Canada ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ uunet!van-bc!twg!bill (604) 431-9600 (voice) | Your Computer bill@twg.bc.ca (604) 430-4329 (fax) | Systems Partner
slootman@dri.nl (Paul Slootman) (05/27/91)
In article <2286@twg.bc.ca> bill@twg.bc.ca (Bill Irwin) writes: >I would like to know if there is a command under SCO XENIX 2.3.3 >that will produce a checksum on a file, so that later, another >checksum could be compared to the first; and if different, you >would know that the file had been modified. There is a command 'sum' that (surprise!) calculates the checksum. Some versions have an option -r that causes an alternative algorithm to be used, which is better at detecting things like swapped bytes and so (I think, not rely on this). SCO Unix has this option, I'm not sure about Xenix. I'm not sure this is the right newsgroup for this... comp.unix.shell? Paul. -- ---------------- :slootman@dri.nl : When you get to the point where you think that nothing :+ 31 5496 88831 : is impossible, try pushing toothpaste back into a tube ----------------
bill@twg.bc.ca (Bill Irwin) (05/28/91)
The answer to this was sitting in my mailbox when I got into the office the morning after posting. Talk about service! There is a "sum" command that will output a checksum for a file. -- Bill Irwin - The Westrheim Group - Vancouver, BC, Canada ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ uunet!van-bc!twg!bill (604) 431-9600 (voice) | Your Computer bill@twg.bc.ca (604) 430-4329 (fax) | Systems Partner
phil@ux1.cso.uiuc.edu (Phil Howard KA9WGN) (05/29/91)
bill@twg.bc.ca (Bill Irwin) writes: >The answer to this was sitting in my mailbox when I got into the >office the morning after posting. Talk about service! > >There is a "sum" command that will output a checksum for a file. This is a useful command, too. For instance I use it in my crosslink script which first checks files for like sizes, and if alike, then it takes the checksum to see if they still might be alike. The first file is summed only once a second file is found of the same size. If the sums match, then the files are compared with "cmp" for the final determination. If they are identical, they are hardlinked. Cuts down on space in some cases. -- /***************************************************************************\ / Phil Howard -- KA9WGN -- phil@ux1.cso.uiuc.edu | Guns don't aim guns at \ \ Lietuva laisva -- Brivu Latviju -- Eesti vabaks | people; CRIMINALS do!! / \***************************************************************************/