A note on vendor reaction speed to the e=3 problem

Leichter, Jerry leichter_jerrold at emc.com
Thu Sep 28 16:47:32 EDT 2006


| > VMS has for years had a simple CHECKSUM command, which had a
| > variant, CHECKSUM/IMAGE, applicable only to executable image files.
| > It knew enough about the syntax of executables to skip over
| > irrelevant metadata like link date and time.  (The checksums
| > computed weren't cryptographic - at least the last time I used it,
| > many years ago.  The command was created to use in patches to
| > provide a quick verification that the file being patched was "the
| > right one".)  I've always found it surprising that no one seems to
| > have developed similar tools for Unix - with the Gnu libraries for
| > portable access to object/ executable files, it could be done
| > relatively easily.
| 
| The "sum" command has existed in Unixes since before VMS
| existed. 
I have yet to see a version of "sum" that understands object or
executable file syntax and skips the "noise" stuff.

|	   Checksum has too many characters in the name ;-).
Yes, but VMS allow you to abbreviate automatically to the shortest
unique name.  Four characters (for top-level commands) is guaranteed
to be sufficient at least among vendor-provided commands, so "chec"
would always be safe.  In practice, I think "ch" was probably enough,
beating out "sum".  :-)  Of course, you could also abbreviate
option names to the shortest unique value, so ch/i would almost
certainly have given you "checksum/image" in even fewer characters
than a hypothetical "sum -i" option for Unix.  :-) :-)

							-- Jerry

| Greg.
| 
| 

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