tail

[pjfarley3 at earthlink.net]

> -----Original Message-----
> From: dn <PythonList at DancesWithMice.info>
> Sent: Saturday, April 23, 2022 6:05 PM
> To: python-list at python.org
> Subject: Re: tail
> 
<Snipped> 
> NB quite a few of IBM's (extensively researched) algorithms which formed utility
> program[me]s on mainframes, made similar such algorithmic choices, in the
> pursuit of efficiencies.

WRT the mentioned IBM utility program[me]s, the non-Posix part of the IBM mainframe file system has always provided record-managed storage since the late 1960's (as opposed to the byte-managed storage of *ix systems) so searching for line endings was (and is) irrelevant and unnecessary in that environment.  That operating system also provides basic "kernel-level" read-backwards API's for the record-managed file system, so there was never any need to build reverse-read into your code for that environment.

The byte-managed file storage used by the Posix kernel running under the actually-in-charge IBM mainframe operating system is, of course, subject to the same constraints and (in)efficiencies discussed in this thread.

Peter
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