BSD & Sys5 Job Control

[Jeffrey Greenberg]

(Caveat: Much of this is from memory! ("Embarassment is the highest
state of conciousness" - Anon.))

shl is a different approach to job control then berkeley's older 
system.  It functions primarily through the terminal driver, then through
kernel signals... that is, there is no SIGSTOP, etc.  It is a far
cleaner an implementation.  The term & col stuff is not kept
in the kernel (it doesn't belong there).

In BSD, processes must be coded to properly handle job control. In sys5,
whoever manipulates the terminal driver, is in control.

However, as is ususal, BSD is far sexier and idiosyncratic.  Job control
for the user is far more usuable.  This is because it is built into csh, and
is all that recommends it.  Sys5's sh & korn-sh (at least ours)
doesn't know about job control so one is left to use the poor 'shl' program.
The 'shl' program is a sketch of a program.  I believe that ATT has
a decent interface somewhere or a shell modified for job control -
there's money to be made with a decent Sys5 job control interface.
Shl is a program that only does the following: create a seperate shell on
same terminal; switch from one to the other; cause them to suspend on
input or output; resume them; and change what - if anything - they'll wait for.
All the functionality one wants.  However, shl is not a real shell, lacking
all the language constructs, aliases, etc.

In summary: I used to use BSD job control but on system 5, with shl, I
do not.  It's too clumsy.
-- 
Jeffrey Greenberg - {cmcl2,allegra}!phri!dolphy!jmg
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