Hi Mark, Aha, that explains the results. That c program and the cl compiler were only used as a way of showing the difference in process ids. The script I am trying to port to run on Windows under cygwin does not really compile C and really needs to run native Windows programs.
Anyhow, thank you very much for a quick reply. Vadym On Wed, 8 Oct 2025 at 06:54, Mark Geisert via Cygwin <[email protected]> wrote: > > Hi Vadym, > > On 10/7/2025 4:38 AM, Vadym Krevs via Cygwin wrote: > > Hi. > > > > I've a question regarding job control in cygwin bash. > > > > Below is a simple program that prints out the process id of itself. > > > > C:\builds>cat a.c > > #include <stdio.h> > > #include <process.h> > > > > int main(int argc, char ** argv) > > { > > printf("pid=%d\n", _getpid()); > > return 0; > > } > > > > Compiling and running it in foreground from cygwin bash works as expected: > > > > user@host /cygdrive/c/builds > > $ cl a.c > > Microsoft (R) C/C++ Optimizing Compiler Version 19.44.35217 for x86 > > Copyright (C) Microsoft Corporation. All rights reserved. > > > > a.c > > Microsoft (R) Incremental Linker Version 14.44.35217.0 > > Copyright (C) Microsoft Corporation. All rights reserved. > > > > /out:a.exe > > a.obj > > > > user@host /cygdrive/c/builds > > $ ./a > > pid=2352 > > > > > > However, if I start it in background and attempt to get back the pid > > of the started process via $!, the result is not what one would > > expect. The actual process pid printed out from my program differs > > from what cygwin bash thinks is "process ID of the job most recently > > placed into the background". > > > > user@host /cygdrive/c/builds > > $ ./a & > > [1] 15909 > > > > user@host /cygdrive/c/builds > > $ pid=27008 > > echo $! > > 15909 > > [1]+ Done ./a > > > > > > So my question is - is this a cygwin bash quirk (i.e. the fact that $! > > is not the pid of the started process) caused by how fork/process > > startup is implemented in cygwin? I have tried reading > > https://cygwin.com/cygwin-ug-net/highlights.html#ov-hi-process but > > could not see anything relevant aside from "Job control works as > > expected in shells that support it." in the Signals section. Is there > > any way to get the actual process pid? > > You are using cl to create the executable, and doing so means it results > in a native Windows program, not a Cygwin program. Running ldd.exe on > your executable will show the Cygwin DLL is not associated. > > If you instead use gcc to create the executable, this testcase works > correctly. Try 'gcc a.c', assuming you have gcc installed (via Cygwin > Setup Program). You will also have to change "<process.h>" to > "<unistd.h" and "_getpid" to "getpid" in your source file first. > HTH, > > ..mark > > -- > Problem reports: https://cygwin.com/problems.html > FAQ: https://cygwin.com/faq/ > Documentation: https://cygwin.com/docs.html > Unsubscribe info: https://cygwin.com/ml/#unsubscribe-simple -- Problem reports: https://cygwin.com/problems.html FAQ: https://cygwin.com/faq/ Documentation: https://cygwin.com/docs.html Unsubscribe info: https://cygwin.com/ml/#unsubscribe-simple
