chain
1. (From {BASIC}'s "CHAIN" statement) To
pass control to a child or successor without going through the
{operating system} {command interpreter} that invoked you.
The state of the parent program is lost and there is no
returning to it. Though this facility used to be common on
memory-limited {microcomputers} and is still widely supported
for {backward compatibility}, the jargon usage is
semi-obsolescent; in particular, {Unix} calls this {exec}.
Compare with the more modern "{subshell}".
2.
A series of linked data areas within an {operating system} or {application program}. "Chain rattling"
is the process of repeatedly running through the linked data
areas searching for one which is of interest. The implication
is that there are many links in the chain.
3. A possibly infinite, non-decreasing sequence of
elements of some {total ordering}, S
x0 <◦ x1 <◦ x2 ...
A chain satisfies:
for all x,y in S, x <◦ y \/ y <◦ x.
I.e. any two elements of a chain are related.
("<◦" is written in {LaTeX} as {\sqsubseteq}).
[{Jargon File}]
(1995-02-03)