@code{exec-path} contains a list of directories to search. Emacs
initializes @code{exec-path} when it starts up, based on the value of
the environment variable @code{PATH}. The standard file name
-constructs, @samp{~}, @samp{.}, and @samp{..}, are interpreted as usual
-in @code{exec-path}, but environment variable substitutions
+constructs, @samp{~}, @samp{.}, and @samp{..}, are interpreted as
+usual in @code{exec-path}, but environment variable substitutions
(@samp{$HOME}, etc.) are not recognized; use
@code{substitute-in-file-name} to perform them (@pxref{File Name
-Expansion}).
+Expansion}). @code{nil} in this list refers to
+@code{default-directory}.
Executing a program can also try adding suffixes to the specified
name:
system-dependent.
@end defvar
+ @strong{Please note:} The argument @var{program} contains only the
+name of the program; it may not contain any command-line arguments. You
+must use @var{args} to provide those.
+
Each of the subprocess-creating functions has a @var{buffer-or-name}
argument which specifies where the standard output from the program will
go. It should be a buffer or a buffer name; if it is a buffer name,
argument, @var{args}. The @var{args} must all be strings, and they are
supplied to @var{program} as separate command line arguments. Wildcard
characters and other shell constructs have no special meanings in these
-strings, since the whole strings are passed directly to the specified
-program.
-
- @strong{Please note:} The argument @var{program} contains only the
-name of the program; it may not contain any command-line arguments. You
-must use @var{args} to provide those.
+strings, since the strings are passed directly to the specified program.
The subprocess gets its current directory from the value of
@code{default-directory} (@pxref{File Name Expansion}).
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
@end smallexample
@end defun
+@defun process-file program &optional infile buffer display &rest args
+This function processes files synchronously in a separate process. It
+is similar to @code{call-process} but may invoke a file handler based
+on the value of the variable @code{default-directory}. The current
+working directory of the subprocess is @code{default-directory}.
+
+The arguments are handled in almost the same way as for
+@code{call-process}, with the following differences:
+
+Some file handlers may not support all combinations and forms of the
+arguments @var{infile}, @var{buffer}, and @var{display}. For example,
+some file handlers might behave as if @var{display} were @code{nil},
+regardless of the value actually passed. As another example, some
+file handlers might not support separating standard output and error
+output by way of the @var{buffer} argument.
+
+If a file handler is invoked, it determines the program to run based
+on the first argument @var{program}. For instance, consider that a
+handler for remote files is invoked. Then the path that is used for
+searching the program might be different than @code{exec-path}.
+
+The second argument @var{infile} may invoke a file handler. The file
+handler could be different from the handler chosen for the
+@code{process-file} function itself. (For example,
+@code{default-directory} could be on a remote host, whereas
+@var{infile} is on another remote host. Or @code{default-directory}
+could be non-special, whereas @var{infile} is on a remote host.)
+
+If @var{buffer} has the form @code{(@var{real-destination}
+@var{error-destination})}, and @var{error-destination} names a file,
+then the same remarks as for @var{infile} apply.
+
+The remaining arguments (@var{args}) will be passed to the process
+verbatim. Emacs is not involved in processing file names that are
+present in @var{args}. To avoid confusion, it may be best to avoid
+absolute file names in @var{args}, but rather to specify all file
+names as relative to @code{default-directory}. The function
+@code{file-relative-name} is useful for constructing such relative
+file names.
+@end defun
+
@defun call-process-region start end program &optional delete destination display &rest args
This function sends the text from @var{start} to @var{end} as
standard input to a process running @var{program}. It deletes the text
@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
subprocess. Processes are deleted automatically after they terminate,
but not necessarily right away. You can delete a process explicitly
at any time. If you delete a terminated process explicitly before it
-is deleted automatically, no harm results. Deletion of a running
+is deleted automatically, no harm results. Deleting a running
process sends a signal to terminate it (and its child processes if
-any), and calls the process sentinel if it has one.
+any), and calls the process sentinel if it has one. @xref{Sentinels}.
- @code{get-buffer-process} and @code{process-list} do not remember a
-deleted process, but the process object itself continues to exist as
-long as other Lisp objects point to it. All the Lisp primitives that
-work on process objects accept deleted processes, but those that do
-I/O or send signals will report an error. The process mark continues
-to point to the same place as before, usually into a buffer where
-output from the process was being inserted.
+ When a process is deleted, the process object itself continues to
+exist as long as other Lisp objects point to it. All the Lisp
+primitives that work on process objects accept deleted processes, but
+those that do I/O or send signals will report an error. The process
+mark continues to point to the same place as before, usually into a
+buffer where output from the process was being inserted.
@defopt delete-exited-processes
This variable controls automatic deletion of processes that have
they exit.
@end defopt
-@defun delete-process name
-This function deletes the process associated with @var{name}, killing
-it with a @code{SIGKILL} signal. The argument @var{name} may be a
-process, the name of a process, a buffer, or the name of a buffer.
-Calling @code{delete-process} on a running process terminates it,
-updates the process status, and runs the sentinel (if any) immediately.
-If the process has already terminated, calling @code{delete-process}
-has no effect on its status, or on the running of its sentinel (which
-will happen sooner or later).
+@defun delete-process process
+This function deletes a process, killing it with a @code{SIGKILL}
+signal. The argument may be a process, the name of a process, a
+buffer, or the name of a buffer. (A buffer or buffer-name stands for
+the process that @code{get-buffer-process} returns.) Calling
+@code{delete-process} on a running process terminates it, updates the
+process status, and runs the sentinel (if any) immediately. If the
+process has already terminated, calling @code{delete-process} has no
+effect on its status, or on the running of its sentinel (which will
+happen sooner or later).
@smallexample
@group
@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:
@end example
@end defun
-@defun set-process-coding-system process decoding-system encoding-system
+@defun set-process-coding-system process &optional decoding-system encoding-system
This function specifies the coding systems to use for subsequent output
from and input to @var{process}. It will use @var{decoding-system} to
decode subprocess output, and @var{encoding-system} to encode subprocess
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
input and make space in the buffer. It also allows filters, sentinels
and timers to run---so take account of that in writing your code.
-@defun process-send-string process-name string
-This function sends @var{process-name} the contents of @var{string} as
-standard input. The argument @var{process-name} must be a process or
-the name of a process. If it is @code{nil}, the current buffer's
-process is used.
+ In these functions, the @var{process} argument can be a process or
+the name of a process, or a buffer or buffer name (which stands
+for a process via @code{get-buffer-process}). @code{nil} means
+the current buffer's process.
+
+@defun process-send-string process string
+This function sends @var{process} the contents of @var{string} as
+standard input. If it is @code{nil}, the current buffer's process is used.
The function returns @code{nil}.
@end smallexample
@end defun
-@defun process-send-region process-name start end
+@defun process-send-region process start end
This function sends the text in the region defined by @var{start} and
-@var{end} as standard input to @var{process-name}, which is a process or
-a process name. (If it is @code{nil}, the current buffer's process is
-used.)
+@var{end} as standard input to @var{process}.
An error is signaled unless both @var{start} and @var{end} are
integers or markers that indicate positions in the current buffer. (It
is unimportant which number is larger.)
@end defun
-@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.
-
- 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
-error is signaled if the current buffer has no process.
+@defun process-send-eof &optional process
+This function makes @var{process} see an end-of-file in its
+input. The @acronym{EOF} comes after any text already sent to it.
- The function returns @var{process-name}.
+The function returns @var{process}.
@smallexample
@group
Each of the signal-sending functions takes two optional arguments:
@var{process-name} and @var{current-group}.
- The argument @var{process-name} must be either a process, the name of
-one, or @code{nil}. If it is @code{nil}, the process defaults to the
-process associated with the current buffer. An error is signaled if
-@var{process-name} does not identify a process.
+ The argument @var{process} must be either a process, a process
+name, a buffer, a buffer name, or @code{nil}. A buffer or buffer name
+stands for a process through @code{get-buffer-process}. @code{nil}
+stands for the process associated with the current buffer. An error
+is signaled if @var{process} does not identify a process.
The argument @var{current-group} is a flag that makes a difference
when you are running a job-control shell as an Emacs subprocess. If it
job-control shells won't work when a pipe is used. See
@code{process-connection-type} in @ref{Asynchronous Processes}.
-@defun interrupt-process &optional process-name current-group
-This function interrupts the process @var{process-name} by sending the
+@defun interrupt-process &optional process current-group
+This function interrupts the process @var{process} by sending the
signal @code{SIGINT}. Outside of Emacs, typing the ``interrupt
character'' (normally @kbd{C-c} on some systems, and @code{DEL} on
others) sends this signal. When the argument @var{current-group} is
on the terminal by which Emacs talks to the subprocess.
@end defun
-@defun kill-process &optional process-name current-group
-This function kills the process @var{process-name} by sending the
+@defun kill-process &optional process current-group
+This function kills the process @var{process} by sending the
signal @code{SIGKILL}. This signal kills the subprocess immediately,
and cannot be handled by the subprocess.
@end defun
-@defun quit-process &optional process-name current-group
+@defun quit-process &optional process current-group
This function sends the signal @code{SIGQUIT} to the process
-@var{process-name}. This signal is the one sent by the ``quit
+@var{process}. This signal is the one sent by the ``quit
character'' (usually @kbd{C-b} or @kbd{C-\}) when you are not inside
Emacs.
@end defun
-@defun stop-process &optional process-name current-group
-This function stops the process @var{process-name} by sending the
+@defun stop-process &optional process current-group
+This function stops the process @var{process} by sending the
signal @code{SIGTSTP}. Use @code{continue-process} to resume its
execution.
subprocess.
@end defun
-@defun continue-process &optional process-name current-group
+@defun continue-process &optional process current-group
This function resumes execution of the process @var{process} by sending
-it the signal @code{SIGCONT}. This presumes that @var{process-name} was
+it the signal @code{SIGCONT}. This presumes that @var{process} was
stopped previously.
@end defun
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 to send signals to processes that are not children of Emacs.
+The @var{process} argument can be a system process @acronym{ID}; that
+allows you to send signals to processes that are not children of
+Emacs.
@end defun
@node Output from Processes
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-@code{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
it decodes the output according to the process output coding system.
If the coding system is @code{raw-text} or @code{no-conversion}, Emacs
converts the unibyte output to multibyte using
-@code{string-to-multibyte}, inserts the resulting multibyte text.
+@code{string-to-multibyte}, and inserts the resulting multibyte text.
You can use @code{set-process-coding-system} to specify which coding
system to use (@pxref{Process Information}). Otherwise, the coding
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 22.1 feature
+If @var{process} is a process, and the argument @var{just-this-one} is
+non-@code{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.
@section Querying Before Exit
When Emacs exits, it terminates all its subprocesses by sending them
-the @code{SIGHUP} signal. Because some subprocesses are doing
+the @code{SIGHUP} signal. Because subprocesses may be doing
valuable work, Emacs normally asks the user to confirm that it is ok
to terminate them. Each process has a query flag which, if
non-@code{nil}, says that Emacs should ask for confirmation before
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.
the process plist, from the server.) The network server then goes
back to listening for more connection requests.
+ Network connections and servers are created by calling
+@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
+one of the @code{open-network-...} functions descibed below;
+internally, they just call @code{make-network-process} with suitable
+arguments.
+
You can distinguish process objects representing network connections
and servers from those representing subprocesses with the
@code{process-status} function. The possible status values for
@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
can increase this limit, unless it is imposed by the operating
-systems.) For a network connection, being stopped means not
+systems.) For a network stream connection, being stopped means not
processing input (any arriving input waits until you resume the
-connection). You can use the function @code{process-command} to
-determine whether a network connection or server is stopped; a
-non-@code{nil} value means yes.
+connection). For a datagram connection, some number of packets may be
+queued but input may be lost. You can use the function
+@code{process-command} to determine whether a network connection or
+server is stopped; a non-@code{nil} value means yes.
@defun open-network-stream name buffer-or-name host service
This function opens a TCP connection, and returns a process object
@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
@end defun
@defun format-network-address address &optional omit-port
-This function converts the lisp representation of a network address to
+This function converts the Lisp representation of a network address to
a string. For example, a five-element vector @code{[@var{a} @var{b}
@var{c} @var{d} @var{p}]} represents an IP address
@var{a}.@var{b}.@var{c}.@var{d} and port number @var{p}.
@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.
HCoop / bpt / emacs.git / blobdiff