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<4b59209a91e8384ec000e2724696791c AT smtp-cloud7 DOT xs4all DOT net> <935d8ce5-fd5c-3010-4664-bb2dc9b7ca2f AT cornell DOT edu> <20190729084552 DOT GL11632 AT calimero DOT vinschen DOT de> <20190729134700 DOT GO11632 AT calimero DOT vinschen DOT de> <20190729152327 DOT GQ11632 AT calimero DOT vinschen DOT de> <20190729154049 DOT GR11632 AT calimero DOT vinschen DOT de> <8e57d4da-722d-1b9a-bd28-5f96ed182f6a AT cornell DOT edu> In-Reply-To: <8e57d4da-722d-1b9a-bd28-5f96ed182f6a@cornell.edu> user-agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 authentication-results: spf=none (sender IP is ) smtp.mailfrom=kbrown AT cornell DOT edu; x-ms-oob-tlc-oobclassifiers: OLM:8273; received-spf: None (protection.outlook.com: cornell.edu does not designate permitted sender hosts) x-ms-exchange-senderadcheck: 1 Content-Type: text/plain; charset="utf-8" Content-ID: <905B3204951F424F8717B757357DF47D AT namprd04 DOT prod DOT outlook DOT com> MIME-Version: 1.0 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: ksb2 AT cornell DOT edu X-IsSubscribed: yes Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from base64 to 8bit by delorie.com id x6VI0xDE007598 On 7/31/2019 11:53 AM, Ken Brown wrote: > On 7/29/2019 2:55 PM, Ken Brown wrote: >> Here's the error that I can reproduce easily in xterm: >> >> $ ls <(grep bash .bashrc) >> /dev/fd/63 >> grep: write error: Broken pipe >> >> This happens 98% of the time. Notice that I used plain 'ls' rather than the >> original 'ls -lL'. With the latter, I get the broken pipe error 60% of the time >> rather than 98%: >> >> $ ls -lL <(grep bash .bashrc) >> pr-------- 1 kbrown None 0 2019-07-29 14:46 /dev/fd/63 >> grep: write error: Broken pipe >> >> What about the explanation I tried earlier, but perhaps not clearly: ls prints >> /dev/fd/63 and then exits, thereby closing the read end of the pipe, while grep >> (running asynchronously) hasn't finished writing to the write end of the pipe. >> >> The fact that I get the broken pipe error more often with plain 'ls' than with >> 'ls -lL' is consistent with that. And the fact that I get no errors with 'cat >> <(grep bash .bashrc)' is also consistent with it, since cat doesn't exit until >> grep has finished writing. >> >> On the other hand, this doesn't explain why I see the error only under xterm, >> nor does it explain why you can't reproduce it at all. > > I've made some progress. It turns out that the problem only occurs in terminals > launched from the xwin-xdg-menu tray icon. I can even launch a mintty window > from that icon (System Tools -> Cygwin Terminal) and I'll see the problem. On > the other hand, I can launch an xterm without using that icon (e.g., 'DISPLAY=:0 > xterm -l&' from a mintty window) and I won't see the problem. > > So the issue has something to do with how xwin-xdg-menu launches applications, > and how that interacts with bash's process substitution. I've just downloaded > the xwin-xdg-menu source and will see if I can figure out what's going on. I've > also added Jon to the CC in case he has a chance to take a look. OK, when xwin-xdg-menu launches an application, it creates two pipes and sets the application's stdout and stderr to the write ends of those pipes. For example, here's what I see when I launch mintty from xwin-xdg-menu: $ pgrep mintty 5375 $ ls -l /proc/5375/fd total 0 lrwxrwxrwx 1 kbrown None 0 2019-07-31 13:37 0 -> /dev/null lrwxrwxrwx 1 kbrown None 0 2019-07-31 13:37 1 -> pipe:[38654736160] lrwxrwxrwx 1 kbrown None 0 2019-07-31 13:37 2 -> pipe:[42949703456] lrwxrwxrwx 1 kbrown None 0 2019-07-31 13:37 3 -> /dev/ptmx lrwxrwxrwx 1 kbrown None 0 2019-07-31 13:37 4 -> /dev/windows These pipes are apparently used for logging. I don't see how this would explain my observations (grep reporting a broken pipe), but it is at least a difference between a terminal started from xwin-xdg-menu and an "ordinary" terminal. Anyway, I don't see any evidence here of a Cygwin bug. Ken -- Problem reports: http://cygwin.com/problems.html FAQ: http://cygwin.com/faq/ Documentation: http://cygwin.com/docs.html Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple