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(emacs)Windows Processes

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Subprocesses on Windows 9X/ME and Windows NT/2K
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   Emacs compiled as a native Windows application (as opposed to the DOS
version) includes full support for asynchronous subprocesses.  In the
Windows version, synchronous and asynchronous subprocesses work fine on
both Windows 9X and Windows NT/2K as long as you run only 32-bit Windows
applications.  However, when you run a DOS application in a subprocess,
you may encounter problems or be unable to run the application at all;
and if you run two DOS applications at the same time in two
subprocesses, you may have to reboot your system.

   Since the standard command interpreter (and most command line
utilities) on Windows 95 are DOS applications, these problems are
significant when using that system.  But there's nothing we can do
about them; only Microsoft can fix them.

   If you run just one DOS application subprocess, the subprocess should
work as expected as long as it is "well-behaved" and does not perform
direct screen access or other unusual actions.  If you have a CPU
monitor application, your machine will appear to be 100% busy even when
the DOS application is idle, but this is only an artifact of the way CPU
monitors measure processor load.

   You must terminate the DOS application before you start any other DOS
application in a different subprocess.  Emacs is unable to interrupt or
terminate a DOS subprocess.  The only way you can terminate such a
subprocess is by giving it a command that tells its program to exit.

   If you attempt to run two DOS applications at the same time in
separate subprocesses, the second one that is started will be suspended
until the first one finishes, even if either or both of them are
asynchronous.

   If you can go to the first subprocess, and tell it to exit, the
second subprocess should continue normally.  However, if the second
subprocess is synchronous, Emacs itself will be hung until the first
subprocess finishes.  If it will not finish without user input, then
you have no choice but to reboot if you are running on Windows 9X.  If
you are running on Windows NT/2K, you can use a process viewer
application to kill the appropriate instance of ntvdm instead (this
will terminate both DOS subprocesses).

   If you have to reboot Windows 9X in this situation, do not use the
`Shutdown' command on the `Start' menu; that usually hangs the system.
Instead, type `CTL-ALT-<DEL>' and then choose `Shutdown'.  That usually
works, although it may take a few minutes to do its job.