[tz] Old timestamps on files

Paul Eggert eggert at cs.ucla.edu
Sat Dec 29 22:48:16 UTC 2018

[Subject line changed from "Re: [tz] Timezone change for Asia/Qyzylorda".]

Guy Harris wrote:
>       $ ls -ld ~/postponed
> 	-rw-------  1 gharris  staff  5509 Oct 11  2007 /Users/gharris/postponed

My personal record for old files is this one:

$ ls -l --time-style=+'%Y-%m-%d %H:%M:%S %z' $HOME/.plan
-r--r--r-- 2 eggert faculty 386 1981-07-14 16:01:39 -0700 /home/eggert/.plan

and yes, 1981 is really when I last changed that file, on a VAX-11/780 running 
4.2BSD when I was teaching at the University of California, Santa Barbara. The 
file is still used when someone fingers me on one of our research machines, or 
when web crawlers visit <https://web.cs.ucla.edu/~eggert/.plan.txt>; the 
plan.txt link is why .plan has a link count of 2 in the above listing. Extra 
credit if you can identify the quote.

One can pretend to have older timestamps by using the utimensat system call, or 
something like it, and this will test the tz database further back. I regularly 
assign to students the problem of setting a file's timestamp to 1918-11-11 11:00 
UT (the end of World War I) and then I ask them why it doesn't work when they 
run their program on a file residing on a Network Appliance file server.

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