[Novalug] tidbit - include the md5sum output when you email attached files to people

Doug Toppin dougtoppin@gmail.com
Fri Jul 17 10:32:30 EDT 2009


Here's a little tidbit - include the md5sum output when you email
attached files to people.  What I mean by that is that when you attach
files to your email you should also include a checksum value of the
file(s) in the email.  An example would look like this:

$ md5sum list.txt
ae034c4c634e21ea23da1f14e358d776  list.txt

md5sum computes a value reflecting the content of the file.  Someone
else that runs md5sum on the file that they receive should get exactly
the same value.  If they get something different there's a very good
chance that something/someone has modified the file in between you
sending it and them receiving it.  This can happen due to completely
innocent (as well as nefarious) reasons.  An example would be if
someone that receives the file saves/forwards it to someone else, it's
possible that their email client or some other action they took might
modify the file.   A text file containing only newlines might get
inadvertently modified to contain carriage return newline and cause
some confusion.  If you include the md5sum output and they check it on
their side before they attempt to use it and see a different value it
would prevent some confusion.
This probably seems obvious to many of you but I thought that I would
pass it along because it's easy to forget about it in the heat of the
moment.

Doug



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