Bugs in the at command - summary

[jpm at BNL.ARPA]

A few weeks ago I asked if anybody knew of bugs in the "at"
command. I got three responses which I am including below.
Sorry for not posting this sooner but this site has been
having problems and every time I get ready to create a
summary something goes wrong (the editor breaks, the disk
breaks, the Arpanet breaks, etc.).


Date:     Sun, 17 Jun 84 2:56:10 EDT
From:     Doug Gwyn (VLD/VMB) <gwyn at Brl-Vld.ARPA>
To:       jpm at bnl.arpa
Subject:  Re: bug in at command

UNIX System III and V do not have an "at" command.
UNIX System V Release 2 provides "user cron tables" which is the
same sort of facility but totally redone.

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From: philabs!decvax!tektronix!jerryp
Date: Monday, 18 Jun 84 08:08:01 PDT
To: decvax!philabs!sbcs!bnl!jpm, jerryp
Subject: Re: bug in at command

John,

We have BSD here, so I'm not sure... but I've heard that the bug
involves quoting of the environment variables in the /usr/spool/at/*
file.  In other words, our version (BSD) of "at" puts statements like this
in the /usr/spool/at/* file:

  SYSPATH='/usr3/jerryp/.bin /usr/local /usr/tek /usr/ucb /bin /usr/bin'

I heard that the bug in other versions of "at" is that they don't quote
the variable strings.  In other words, the file would have

  SYSPATH=/usr3/jerryp/.bin /usr/local /usr/tek /usr/ucb /bin /usr/bin

...and, when atrun tries to execute the /usr/spool/at/* file, and the shell
reads a line like that, with blanks, it chokes.

--Jerry Peek, UNIX Training Instructor, Tektronix, Inc.
uucp:      {allegra,decvax,hplabs,ihnp4,mit-eddie,ucbvax}!tektronix!jerryp
ARPAnet:   jerryp.tek at csnet-relay

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Date: Mon, 18 Jun 84 22:22:23 edt
From: yba at mit-athena (Mark H Levine)
To: jpm at BNL.ARPA
Subject: Re: bug in at command

The bug I am most fond of in "at" is that it did not quote shell variables
in the generated script.  In more detail:

Say your prompt is set to the character greater-than, ">".

You run an "at" command creating a file in /usr/spool/at that begins:

PS1=>

which causes a syntax error in the shell, and the at file dies quickly and
quietly having done nothing.  A fix to this was to force quoting of all
arguments which were invisibly set for the user in order to guarantee the
"at" command ran in the same environment in which the request was made,
that is the above would begin:

PS1=">"

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