On Wed, Nov 29, 2017 at 6:03 AM, Noel Chiappa <jnc@mercury.lcs.mit.edu> wrote:
    > From: Charles Anthony

    > Entry points are usually defined as "foo$bar", where "foo" is the
    > segment name, and "bar" an entry point in the segment symbol table. I
    > believe that the degerate case of "foo$" is treated as "foo$foo" by the
    > shell.

So I'm curious about how this, and additional names, interact. (For those who
aren't familiar with Multics, a segment [file, sort of] can have multiple
names. This is sort of like 'hard links' in Unix, except that in Multics one
name, the "primary name" is very slightly preeminent. See here:


page 2-5, for more, if you're interested.)

They are also different in an important way: the additional name is part of the segment, not of the directory. If the segment is moved to a different directory, the names move with it.
So if I have a segment with primary name 'foo', and additional names 'bar' and
'zap', and I say 'zap' to the Multics shell, I assume it does a call to
zap$zap, which finds the segment with the primary name 'foo', and calls the
'zap' entry therein?

Turns out that it does (I thought it didn't, but I checked first).

Multics has a search path mechanism (like $PATH); the directories listed therein are searched for a matching segment name or additional name.

For the hello$world example, the command "an hello world" would add the name "world" to the "hello" segment and then the command "world" would become equivalent to "hello$world".

For the case of "bound" segments, (several object segments linked together in a single segment, and the intersegment links "pre-snapped", the binder control file (similar to ld's ifile) would list the entry points that were to be made externally visible, and the binder automatically adds those names to the the bound segment:

Eg, teco lines in "bound_teco"; the "ls" command sees that "teco" is a name of the "bound_teco" segment.

ls >tools>teco

Segments = 1, Lengths = 9.

re     9  bound_teco_

    > Multics rulez; UNIX droolz

Dude, you clearly have Very Large brass ones to send that to this list! :-)

Thank you (I think). Should be a nice change from the Microsoft fan boys, tho.

-- Charles