On 5/19/2020 11:20 AM, Morten Kjærulff wrote:
On Tue, May 19, 2020 at 3:55 PM Ken Brown via Cygwin <cygwin@cygwin.com> wrote:
On 5/19/2020 7:26 AM, Morten Kjærulff via Cygwin wrote:
Hi,
The following script:
#!/bin/sh
rm -f t.pip t.txt
mkfifo t.pip
printf "line1\nline2\n" >t.txt
ps
{
while true ; do
cp t.txt t.pip
done
} &
rm -f t.rc.*
for rc in 0 1 2 3 4 5 6 7 8 9 ; do
{
diff t.pip t.txt
echo $? >t.rc.$rc
}
done
echo result1 start
ls t.rc.* | wc -l
cat t.rc.*
echo result1 end
rm -f t.rc.*
for rc in 0 1 2 3 4 5 6 7 8 9 ; do
{
diff t.pip t.txt
echo $? >t.rc.$rc
} & # run the readers in parallel
done
sleep 10
echo result2 start
ls t.rc.* | wc -l
cat t.rc.*
echo result2 end
ps
Give me output like this:
$ ./tpip.sh
PID PPID PGID WINPID TTY UID STIME COMMAND
1642 1600 1642 65264 cons1 1058872 13:18:58 /usr/bin/sh
1600 1 1600 72728 cons1 1058872 13:18:33 /usr/bin/bash
1645 1642 1642 42088 cons1 1058872 13:18:58 /usr/bin/ps
result1 start
10
0
0
0
0
0
0
0
0
0
0
result1 end
0a1,2
line1
line2
diff: t.pip
result2 start
1
2
result2 end
PID PPID PGID WINPID TTY UID STIME COMMAND
1690 1688 1642 104032 cons1 1058872 13:19:01 /usr/bin/diff
1681 1642 1642 95012 cons1 1058872 13:19:00 /usr/bin/sh
1642 1600 1642 65264 cons1 1058872 13:18:58 /usr/bin/sh
1684 1681 1642 99624 cons1 1058872 13:19:00 /usr/bin/diff
1678 1676 1642 94532 cons1 1058872 13:19:00 /usr/bin/diff
1688 1642 1642 88864 cons1 1058872 13:19:01 /usr/bin/sh
1698 1642 1642 104820 cons1 1058872 13:19:11 /usr/bin/ps
1692 1642 1642 66572 cons1 1058872 13:19:01 /usr/bin/sh
1677 1674 1642 86692 cons1 1058872 13:19:00 /usr/bin/diff
1646 1642 1642 30888 cons1 1058872 13:18:58 /usr/bin/sh
1600 1 1600 72728 cons1 1058872 13:18:33 /usr/bin/bash
1686 1685 1642 14320 cons1 1058872 13:19:01 /usr/bin/diff
1685 1642 1642 25608 cons1 1058872 13:19:00 /usr/bin/sh
1676 1642 1642 104212 cons1 1058872 13:19:00 /usr/bin/sh
1689 1642 1642 98004 cons1 1058872 13:19:01 /usr/bin/sh
1674 1642 1642 44152 cons1 1058872 13:19:00 /usr/bin/sh
1680 1646 1642 28224 cons1 1058872 13:19:00 /usr/bin/cp
1682 1679 1642 43612 cons1 1058872 13:19:00 /usr/bin/diff
1694 1692 1642 67736 cons1 1058872 13:19:01 /usr/bin/diff
1683 1642 1642 93544 cons1 1058872 13:19:00 /usr/bin/sh
1679 1642 1642 90188 cons1 1058872 13:19:00 /usr/bin/sh
1691 1689 1642 68560 cons1 1058872 13:19:01 /usr/bin/diff
1687 1683 1642 83952 cons1 1058872 13:19:01 /usr/bin/diff
$
That is, when I run the readers in sequence, no problem, but when I
run the in parallel, they either hang or t.pip seems empty.
The current cygwin release doesn't support multiple concurrent readers of a
FIFO. I have recently added that support, which should appear in the next
release, although there are still bugs to be fixed. See
https://cygwin.com/pipermail/cygwin-patches/2020q2/010195.html
Ken
Great!
Let's keep the discussion on the mailing list
Then we will have a read-only file (pipe), which is the output of an
abitrary command, right?
Yes.
Can we have multiple concurrent writers and one reader, which would
become a write-only file, which becomes the input of an abitrary
command?
That already exists, although I found and fixed some bugs when I was developing
the multiple reader support.
Anywhere I can see the plans for next release, if any?
That's up to Corinna.
Ken
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