From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=5.0 tests=MAILING_LIST_MULTI, RCVD_IN_DNSWL_NONE autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 22643 invoked from network); 8 Dec 2020 19:21:39 -0000 Received: from minnie.tuhs.org (45.79.103.53) by inbox.vuxu.org with ESMTPUTF8; 8 Dec 2020 19:21:39 -0000 Received: by minnie.tuhs.org (Postfix, from userid 112) id 239FD94500; Wed, 9 Dec 2020 05:21:37 +1000 (AEST) Received: from minnie.tuhs.org (localhost [127.0.0.1]) by minnie.tuhs.org (Postfix) with ESMTP id 0DF23944D5; Wed, 9 Dec 2020 05:21:12 +1000 (AEST) Received: by minnie.tuhs.org (Postfix, from userid 112) id 2FC47944D4; Wed, 9 Dec 2020 05:21:05 +1000 (AEST) Received: from pio-pvt-msa1.bahnhof.se (pio-pvt-msa1.bahnhof.se [79.136.2.40]) by minnie.tuhs.org (Postfix) with ESMTPS id CB2CC944D3 for ; Wed, 9 Dec 2020 05:21:03 +1000 (AEST) Received: from localhost (localhost [127.0.0.1]) by pio-pvt-msa1.bahnhof.se (Postfix) with ESMTP id 80CE142634 for ; Tue, 8 Dec 2020 20:20:58 +0100 (CET) X-Virus-Scanned: Debian amavisd-new at bahnhof.se Received: from pio-pvt-msa1.bahnhof.se ([127.0.0.1]) by localhost (pio-pvt-msa1.bahnhof.se [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id e70GG9jSV3B9 for ; Tue, 8 Dec 2020 20:20:57 +0100 (CET) Received: by pio-pvt-msa1.bahnhof.se (Postfix) with ESMTPA id 535BE42631 for ; Tue, 8 Dec 2020 20:20:57 +0100 (CET) Received: from localhost (localhost [127.0.0.1]) by localhost (Postfix) with ESMTPS id 2FE662E0305 for ; Tue, 8 Dec 2020 20:20:55 +0100 (CET) Date: Tue, 8 Dec 2020 19:20:54 +0000 From: Michael =?utf-8?B?S2rDtnJsaW5n?= To: tuhs@minnie.tuhs.org Message-ID: References: <20201208190539.GA3303@mcvoy.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20201208190539.GA3303@mcvoy.com> Subject: Re: [TUHS] Were cron and at done at the same time? Or one before the other? X-BeenThere: tuhs@minnie.tuhs.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: The Unix Heritage Society mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: tuhs-bounces@minnie.tuhs.org Sender: "TUHS" On 8 Dec 2020 11:05 -0800, from lm@mcvoy.com (Larry McVoy): > Doesn't it stand to reason that cron would come first, isn't at implemented > with an entry in a crontab? I don't know if it is implemented that way, but if you have cron, then I suspect you could implement some form of at with even a pretty simple shell script that runs once a minute (via cron) to parse a set of files to see what should be run now as opposed to later. If you have at but not cron, then implementing the other doesn't seem quite as straightforward. It would certainly still be possible, but it would definitely give rise to the question of "wouldn't it be real nice if I could set this task up to run on a recurring basis?" followed by "wouldn't it make more sense for the run-stuff-at-some-time task to run from the recurring-execution tool, than the other way around?". Certainly the step from cron to at seems fairly obvious; not all tasks that are to be executed at some point in time lend themselves well to a recurring nature. Sometimes you really want to do something just once, just not right now. -- Michael Kjörling • https://michael.kjorling.se • michael@kjorling.se “Remember when, on the Internet, nobody cared that you were a dog?”