On Tue, Oct 04, 2011 at 04:33:33PM +0200, Marco Atzeri wrote: >On 10/4/2011 4:09 PM, Christopher Faylor wrote: >> On Tue, Oct 04, 2011 at 04:00:13PM +0200, Marco Atzeri wrote: >>> On 10/4/2011 3:53 PM, Peter Rosin wrote: >>>> Peter Rosin skrev 2011-09-28 17:26: >>>>> Hi! >>>>> >>>>> When I use bash to build pipelines, they sometimes don't finish but >>>>> instead some process remains running. Example: >>>>> >>>>> $ tail -f -n 10000 log.txt | grep . | head -n 2 >>>>> >>>>> Almost instantly I get the expected two lines of output, but no prompt >>>>> back. I have to use ctrl-c. If I don't ctrl-c I can run pstree in >>>>> another terminal and see this: >>>>> >>>>> $ pstree >>>>> ??????????mintty?????????bash?????????tail >>>>> ??????mintty?????????bash?????????pstree >>>> >>>> This example is a poor one, as tail simply waits for a new line, when it >>>> gets a new line it forwards it to the pipe and promptly receives a >>>> SIGPIPE as grep is not there anymore. >>>> >>>> I'll get back when I have distilled a better STC. If I can... >>> >>> Hi Peter, >>> are you referring on something like SIGHUP on PTY closure ? >>> >>> http://cygwin.com/ml/cygwin/2011-07/msg00295.html >>> http://pubs.opengroup.org/onlinepubs/9699919799/functions/close.html >> >> Note that this thread contains your assertion that something isn't >> happening correctly but it isn't clear that your analysis is correct. >> >> But, no, SIGPIPE != SIGHUP and the above example clearly shows a >> completely different scenario than what is described in the above >> thread. >> >> cgf > >Hi Cgf, >I know that SIGPIPE != SIGHUP, but Peter mentioned that the example >is not really representative of the PIPE problem he found, so eventually >he catched the same problem I saw on mc. >Of course, it could be a different one. > >Referring to the SIGHUP thread >This portion of the standard, if I am not wrong, >it is not currently implemented in cygwin: > >"If fildes refers to the master side of a pseudo-terminal, and this is >the last close, a SIGHUP signal shall be sent to the controlling >process, if any, for which the slave side of the pseudo-terminal is the >controlling terminal. It is unspecified whether closing the master side >of the pseudo-terminal flushes all queued input and output."
As I mentioned in the thread, that is supposed to be implemented in Cygwin. I could never see a case where it wasn't sent. cgf -- 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
