crontab update

[Guy Harris]

 >>>>The *only* documented and reliable ways of getting cron to recognize
 >>>>a new crontab is to use the crontab command.
 >>
 >>Or become root, kill cron, change/add/delete crontab stuff, and re-invoke
 >>cron.  Violent, but effective.  Not, perhaps, documented, but reliable.
 >>Quite.
 >
 >I just did this the other day. I'm on a Sun 3/60. I updated crontab then
 >sent a Hangup Signal to the cron process with:

Once again, the fact that there are (at least) two different flavors of
"cron" out there leads to confusion....

The first assertion above ("The *only* documented...") applies to the
System V Release 2 and later flavor, which appears in some UNIX systems
(most, if not all, of those that advertise themselves as S5R2 or later,
as well as SunOS 4.x).

The second assertion applies (barring a *big* surprise) to all flavors.

The third assertion ("I updated crontab then sent a Hangup Signal...")
applies to the 4.xBSD "cron" and maybe the V7 "cron" (I no longer have
it handy to check), which appears in some UNIX systems (most of those
that advertise themselves as 4.xBSD, including SunOS prior to SunOS 4.x
which still had "UNIX 4.2BSD" or something like that in its startup
message).

The first assertion does not apply to the 4.xBSD "cron"; there is no
"crontab" command in 4.xBSD.

The second assertion does not apply to the S5R2-and-later "cron"; it
*ignores* the hangup signal.