Re: [TUHS] head/sed/tail (was The Unix shell: a 50-year view)

["Nelson H. F. Beebe" <beebe@math.utah.edu>]

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Doug McIlroy asks about the Rosetta Stone table relating TOPS-20
commands to Unix command in my ``Unix for TOPS-20 Users'' document:

>> I was puzzled, though, by the Unix command "leave", which is 
>> not in the manuals I edited, nor is it in Linux. What does 
>> (or did) it do?

I reread that 1987 document this morning, and found a few small
mistakes, but on the whole, I still agree with what I wrote 34 years
ago, and I'm pleased that almost everything there about Unix still
applies today.

I confess that I had forgotten about the TOPS-20 ALERT command and its
Unix equivalent, leave.  As Doug noted, leave is not in Linux systems,
but it still exists in the BSD world, in DragonFlyBSD, FreeBSD,
NetBSD, OpenBSD, and their many derivatives.  From a bleeding-edge
FreeBSD 14 system, I find

% man leave
LEAVE(1)                FreeBSD General Commands Manual               LEAVE(1)

NAME
     leave – remind you when you have to leave

SYNOPSIS
     leave [[+]hhmm]

DESCRIPTION
     The leave utility waits until the specified time, then reminds you that
     you have to leave.  You are reminded 5 minutes and 1 minute before the
     actual time, at the time, and every minute thereafter.  When you log off,
     leave exits just before it would have printed the next message.
...

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