Talk:Cron
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I wrote this article, adapting from something written a while back, because, to me, cron is the main topic, not crontab. I am sketchy on what came before V7 and "Kernighan's cron" as we called it at Purdue and also a bit sketchy on the subsequent implementations. I hope others can round this out. I didn't really know that my cron got into "the real Unix" until I took a job at SGI in 1990 and looked at the source code and instantly recognized the awful coding style (no spaces, lots of asterisks in comments) I used as a grad student. I think Keith wrote the hardest part: figuring out the NEXT minute in the future that any particular crontab entry should be run, with out walking forward minute-by-minute asking the binary question, "now?" It took a while to debug that.
A few years back I tried to convince the Purdue Research Foundation that they should claim title to the Unix cron but we didn't save notebooks or even e-mails from those days...this was 1979!! So they chose to just let it fall by. I suspect a lot of code in Unix was written by grad students like me and Keith. Another one of those "warm up project" I designed was given to Chris Kent/Kantarjiev and the "pg" command in Unix came out of it. But everyone uses "more" now...though I believe pg was the first paginator that would allow you to go backwards, even if you piped output to it!
I apologize for any deviations from standards and style and decorum and trust the community will correct these or instruct me on how to do so...or both!
Rlb408 02:11, 9 February 2007 (UTC)
Unsure why someone added the description of the crontab fields at the top of the article. This topic is cron, not crontab. The format of cron's spec file is incidental to the topic and I think distracts. Since there is a separate article on crontab and this artile is about the history and algorithm, can we just delete the crontab format description from here? As an analogy, if there were an article about compiler optimization algorithms, would you put a description of the syntax of the language itself in that article? How very odd.
Rlb408 07:32, 17 February 2007 (UTC)
[edit] cron and DST changes
Is Vixie cron the only cron that can not tolerate changes to daylight savings time rules while running? (See http://doughboy.wordpress.com/2007/03/14/vixie-cron-and-the-new-us-dst/.) If so, maybe a note belongs there. If it affects many crons, then a note should go here.--Theodore Kloba 13:59, 26 March 2007 (UTC)
