No problem. I can see wanting the pipe to eork the opposite way. Willard Sent from Samsung tablet
-------- Original message -------- From Russell Davis <rkda...@burninghorse.com> Date: 01/09/2017 5:47 PM (GMT-07:00) To Model 100 Discussion <m100@lists.bitchin100.com> Subject Re: [M100] THAT didn't work... ;-) ah ok. i'd been fiddling with pipes, sockets and fifos aloy recently and in workaround mode so misread your post bst rgrds Russell On 1/9/2017 6:53 PM, Willard Goosey wrote: Huh? No the behavior of the pipe itself is perfect! Date blocked on the pipe *before getting the time* so it could sit there for days and still report current time when the pipe is finally read. It's just that something on the mono/laddiealpha/tsdos train doesn't like the file it's reading changing size while its being read. Which was not an issue the pdd protocol ever imagined. Willard Sent from Samsung tablet -------- Original message -------- From Russell Davis <rkda...@burninghorse.com> Date: 01/09/2017 2:25 PM (GMT-07:00) To Model 100 Discussion <m100@lists.bitchin100.com> Subject Re: [M100] THAT didn't work... ;-) if you want to be able to write to a named pipe before your reader is created you have to open the named pipe as read/write using an extra step e.g. --- pi@glooston:~/GnuCOBOL/open-cobol-code/branches/gnu-cobol-2.0 $ mkfifo foo pi@glooston:~/GnuCOBOL/open-cobol-code/branches/gnu-cobol-2.0 $ exec 3<>./foo pi@glooston:~/GnuCOBOL/open-cobol-code/branches/gnu-cobol-2.0 $ date > ./foo & [1] 2561 pi@glooston:~/GnuCOBOL/open-cobol-code/branches/gnu-cobol-2.0 $ date Mon 9 Jan 21:21:53 UTC 2017 [1]+ Done date > ./foo pi@glooston:~/GnuCOBOL/open-cobol-code/branches/gnu-cobol-2.0 $ cat ./foo Mon 9 Jan 21:21:49 UTC 2017 ^C pi@glooston:~/GnuCOBOL/open-cobol-code/branches/gnu-cobol-2.0 $ rm foo pi@glooston:~/GnuCOBOL/open-cobol-code/branches/gnu-cobol-2.0 $ mkfifo foo pi@glooston:~/GnuCOBOL/open-cobol-code/branches/gnu-cobol-2.0 $ date > ./foo & [1] 2567 pi@glooston:~/GnuCOBOL/open-cobol-code/branches/gnu-cobol-2.0 $ date Mon 9 Jan 21:22:34 UTC 2017 pi@glooston:~/GnuCOBOL/open-cobol-code/branches/gnu-cobol-2.0 $ cat ./foo Mon 9 Jan 21:22:43 UTC 2017 [1]+ Done date > ./foo pi@glooston:~/GnuCOBOL/open-cobol-code/branches/gnu-cobol-2.0 $ ---- although that brings up another problem in that ^C needed to kill the reader unless you background the reader. bst rgrds Russell On 1/9/2017 4:04 PM, Willard Goosey wrote: So I tried a clever trick and it didn't work. (This is NOT a bug report about any of the named programs, as it's a weird edge case.) So UNIX (and therefore Linux) has these things called "named pipes". They're like files, except that they're strictly buffers -- you write something to one and it's only there until it's read. galvatron:~$ mkfifo foo galvatron:~$ date > foo & [1] 395 galvatron:~$ date Mon Jan 9 13:52:21 MST 2017 galvatron:~$ cat foo Mon Jan 9 13:52:23 MST 2017 [1]+ Done date >foo galvatron:~$ So, interestingly, note that the date written to the named pipe "foo" wasn't written until it was read! Just as an experiment, I created ~/root/DATE.DO as a named pipe and redirected date(1) into it... Then tried to read it from tsdos via the laddiealpha PDD server. The result: M100 visits Cold Start City. Not really surprising, something probably got confused by the fact that the named pipe is reported as a 0-length file. Would be an easy way to sync the M100's time to a laddiealpha server, but it's not to be. Willard
