the buffer as output is inserted. (However, if the coding system chosen
for decoding output is @code{undecided}, meaning deduce the encoding
from the actual data, then redisplay sometimes cannot continue once
-non-@sc{ascii} characters are encountered. There are fundamental
+non-@acronym{ASCII} characters are encountered. There are fundamental
reasons why it is hard to fix this; see @ref{Output from Processes}.)
Otherwise the function @code{call-process} does no redisplay, and the
@defun call-process-shell-command command &optional infile destination display &rest args
This function executes the shell command @var{command} synchronously
-in separate process. The final arguments @var{args} are additional
+in a separate process. The final arguments @var{args} are additional
arguments to add at the end of @var{command}. The other arguments
are handled as in @code{call-process}.
@end defun
@defvar process-connection-type
@cindex pipes
-@cindex @sc{pty}s
+@cindex @acronym{PTY}s
This variable controls the type of device used to communicate with
-asynchronous subprocesses. If it is non-@code{nil}, then @sc{pty}s are
+asynchronous subprocesses. If it is non-@code{nil}, then @acronym{PTY}s are
used, when available. Otherwise, pipes are used.
-@sc{pty}s are usually preferable for processes visible to the user, as
+@acronym{PTY}s are usually preferable for processes visible to the user, as
in Shell mode, because they allow job control (@kbd{C-c}, @kbd{C-z},
etc.) to work between the process and its children, whereas pipes do
not. For subprocesses used for internal purposes by programs, it is
often better to use a pipe, because they are more efficient. In
-addition, the total number of @sc{pty}s is limited on many systems and
+addition, the total number of @acronym{PTY}s is limited on many systems and
it is good not to waste them.
The value of @code{process-connection-type} takes effect when
@end smallexample
To determine whether a given subprocess actually got a pipe or a
-@sc{pty}, use the function @code{process-tty-name} (@pxref{Process
+@acronym{PTY}, use the function @code{process-tty-name} (@pxref{Process
Information}).
@end defvar
@end defun
@defun process-id process
-This function returns the @sc{pid} of @var{process}. This is an
+This function returns the @acronym{PID} of @var{process}. This is an
integer that distinguishes the process @var{process} from all other
processes running on the same computer at the current time. The
-@sc{pid} of a process is chosen by the operating system kernel when the
+@acronym{PID} of a process is chosen by the operating system kernel when the
process is started and remains constant as long as the process exists.
@end defun
@end defun
@defun process-coding-system process
+@anchor{Coding systems for a subprocess}
This function returns a cons cell describing the coding systems in use
for decoding output from @var{process} and for encoding input to
@var{process} (@pxref{Coding Systems}). The value has this form:
data appears on the ``standard input'' of the subprocess.
Some operating systems have limited space for buffered input in a
-@sc{pty}. On these systems, Emacs sends an @sc{eof} periodically amidst
+@acronym{PTY}. On these systems, Emacs sends an @acronym{EOF} periodically amidst
the other characters, to force them through. For most programs,
-these @sc{eof}s do no harm.
+these @acronym{EOF}s do no harm.
Subprocess input is normally encoded using a coding system before the
subprocess receives it, much like text written into a file. You can use
@defun process-send-eof &optional process-name
This function makes @var{process-name} see an end-of-file in its
-input. The @sc{eof} comes after any text already sent to it.
+input. The @acronym{EOF} comes after any text already sent to it.
If @var{process-name} is not supplied, or if it is @code{nil}, then
-this function sends the @sc{eof} to the current buffer's process. An
+this function sends the @acronym{EOF} to the current buffer's process. An
error is signaled if the current buffer has no process.
The function returns @var{process-name}.
This function sends a signal to process @var{process}. The argument
@var{signal} specifies which signal to send; it should be an integer.
-You can specify the target process by its process @sc{id}; that allows
+You can specify the target process by its process @acronym{ID}; that allows
you to send signals to processes that are not children of Emacs.
@end defun
can arrive before you finish, if the code in between does not call any
primitive that waits.
+@defvar process-adaptive-read-buffering
+On some systems, when Emacs reads the output from a subprocess, the
+output data is read in very small blocks, potentially resulting in
+very poor performance. This behaviour can be remedied to some extent
+by setting the variable @var{process-adaptive-read-buffering} to a
+non-nil value (the default), as it will automatically delay reading
+from such processes, thus allowing them to produce more output before
+Emacs tries to read it.
+@end defvar
+
It is impossible to separate the standard output and standard error
streams of the subprocess, because Emacs normally spawns the subprocess
inside a pseudo-TTY, and a pseudo-TTY has only one output channel. If
you want to keep the output to those streams separate, you should
-redirect one of them to a file--for example, by using an appropriate
+redirect one of them to a file---for example, by using an appropriate
shell command.
@menu
explicitly permit output to arrive at a specific point, or even to wait
until output arrives from a process.
-@defun accept-process-output &optional process seconds millisec
+@defun accept-process-output &optional process seconds millisec just-this-one
This function allows Emacs to read pending output from processes. The
output is inserted in the associated buffers or given to their filter
functions. If @var{process} is non-@code{nil} then this function does
of a second; on those that do not, you get an error if you specify
nonzero @var{millisec}.
+@c Emacs 21.4 feature
+If @var{process} is a process, and the argument @var{just-this-one} is
+non-nil, only output from that process is handled, suspending output
+from other processes until some output has been received from that
+process or the timeout expires. If @var{just-this-one} is an integer,
+also inhibit running timers. This feature is generally not
+recommended, but may be necessary for specific applications, such as
+speech synthesis.
+
The function @code{accept-process-output} returns non-@code{nil} if it
did get some output, or @code{nil} if the timeout expired before output
arrived.
A network connection is handled by Lisp much like a subprocess, and is
represented by a process object. However, the process you are
communicating with is not a child of the Emacs process, so it has no
-process @sc{id}, and you can't kill it or send it signals. All you
+process @acronym{ID}, and you can't kill it or send it signals. All you
can do is send and receive data. @code{delete-process} closes the
connection, but does not kill the program at the other end; that
program must decide what to do about closure of the connection.
@code{make-network-process} with an argument list consisting of
keyword/argument pairs, for example @code{:server t} to create a
server process, or @code{:type 'datagram} to create a datagram
-connection. @xref{Low-Level Network} for details. You can also use
+connection. @xref{Low-Level Network}, for details. You can also use
one of the @code{open-network-...} functions descibed below;
internally, they just call @code{make-network-process} with suitable
arguments.
@code{listen}. None of those values is possible for a real
subprocess. @xref{Process Information}.
- You can stop and resume operation of a network processes by calling
+ You can stop and resume operation of a network process by calling
@code{stop-process} and @code{continue-process}. For a server
process, being stopped means not accepting new connections. (Up to 5
connection requests will be queued for when you resume the server; you
@defun open-network-stream-server name buffer-or-name service &optional sentinel filter
Create a network server process for a TCP service.
-It returns nil if server processes are not supported; otherwise,
+It returns @code{nil} if server processes are not supported; otherwise,
it returns a subprocess-object to represent the server.
When a client connects to the specified service, Emacs creates a new
@end defun
@node Datagrams
-@section Datagrams
+@section Datagrams
@cindex datagrams
- A datagram connection communicates with individual packets
-rather than streams of data. Each call to @code{process-send}
-sends one datagram packet, and each datagram received results
-in one call to the filter function.
+ A datagram connection communicates with individual packets rather
+than streams of data. Each call to @code{process-send} sends one
+datagram packet (@pxref{Input to Processes}), and each datagram
+received results in one call to the filter function.
The datagram connection doesn't have to talk with the same remote
peer all the time. It has a @dfn{remote peer address} which specifies
@item
An ``unsupported family'' address is represented by a cons
@code{(@var{f} . @var{av})}, where @var{f} is the family number and
-@var{av} is a vector specifying the socket address using with one
-element per address data byte. Do not rely on this format in portable
-code, as it may depend on implementation defined constants, data
-sizes, and data structure alignment.
+@var{av} is a vector specifying the socket address using one element
+per address data byte. Do not rely on this format in portable code,
+as it may depend on implementation defined constants, data sizes, and
+data structure alignment.
@end itemize
@item :nowait @var{bool}
@item :bindtodevice @var{device-name}
If @var{device-name} is a non-empty string identifying a network
interface name (see @code{network-interface-list}), only handle
-packets received on that interface. If @var{device-name} is nil (the
-default), handle packets received on any interface.
+packets received on that interface. If @var{device-name} is @code{nil}
+(the default), handle packets received on any interface.
Using this option may require special privileges on some systems.
@item :keepalive @var{keepalive-flag}
If @var{keepalive-flag} is non-@code{nil} for a stream connection,
-enable exchange of low-level keep-alive messa
+enable exchange of low-level keep-alive messages.
@item :linger @var{linger-arg}
If @var{linger-arg} is non-@code{nil}, wait for successful
@end table
The original argument list, modified with the actual connection
-information, is available via the `process-contact' function.
+information, is available via the @code{process-contact} function.
@end defun
@defun set-network-process-option process option value
@var{option} and their corresponding values @var{value}.
The current setting of an option is available via the
-`process-contact' function.
+@code{process-contact} function.
@end defun
@defun network-interface-list
@example
(featurep 'make-network-process '(@var{keyword} @var{value}))
-@end example
+@end example
@noindent
The result of the first form is @code{t} if it works to specify
@example
(featurep 'make-network-process '@var{keyword})
-@end example
+@end example
Here are some of the option @var{keyword}s you can test in
this way.