@c -*-texinfo-*-
@c This is part of the GNU Emacs Lisp Reference Manual.
-@c Copyright (C) 1990-1995, 1998-1999, 2001-2014 Free Software
+@c Copyright (C) 1990-1995, 1998-1999, 2001-2016 Free Software
@c Foundation, Inc.
@c See the file elisp.texi for copying conditions.
@node Processes
@node Subprocess Creation
@section Functions that Create Subprocesses
+@cindex create subprocess
+@cindex process creation
There are three primitives that create a new subprocess in which to run
a program. One of them, @code{start-process}, creates an asynchronous
Precisely what this function does depends on your operating system. The
function is designed to work with the syntax of your system's standard
shell; if you use an unusual shell, you will need to redefine this
-function.
+function. @xref{Security Considerations}.
@example
;; @r{This example shows the behavior on GNU and Unix systems.}
a shell command:
@example
-(concat "diff -c "
+(concat "diff -u "
(shell-quote-argument oldfile)
" "
(shell-quote-argument newfile))
Insert the output in that buffer, before point. This includes both the
standard output stream and the standard error stream of the process.
-@item a string
+@item a buffer name (a string)
Insert the output in a buffer with that name, before point.
@item @code{t}
@c It actually uses shell-command-switch, but no need to mention that here.
@end defun
-@defun call-process-shell-command command &optional infile destination display &rest args
+@defun call-process-shell-command command &optional infile destination display
This function executes the shell command @var{command} synchronously.
-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}.
+The arguments are handled as in @code{call-process}. An old calling
+convention allowed to pass any number of additional arguments after
+@var{display}, which were concatenated to @var{command}; this is still
+supported, but strongly discouraged.
@end defun
-@defun process-file-shell-command command &optional infile destination display &rest args
+@defun process-file-shell-command command &optional infile destination display
This function is like @code{call-process-shell-command}, but uses
@code{process-file} internally. Depending on @code{default-directory},
-@var{command} can be executed also on remote hosts.
+@var{command} can be executed also on remote hosts. An old calling
+convention allowed to pass any number of additional arguments after
+@var{display}, which were concatenated to @var{command}; this is still
+supported, but strongly discouraged.
@end defun
@defun shell-command-to-string command
Information}).
@end defvar
+@defun make-process &rest args
+This function is like @code{start-process}, but takes keyword arguments.
+
+The arguments @var{args} are a list of keyword/argument pairs.
+Omitting a keyword is always equivalent to specifying it with value
+@code{nil}. Here are the meaningful keywords:
+
+@table @asis
+@item :name @var{name}
+Use the string @var{name} as the process name. It is modified if
+necessary to make it unique.
+
+@item :buffer @var{buffer}
+Use @var{buffer} as the process buffer.
+
+@item :command @var{command}
+Use @var{command} as the command line of the process. @var{command}
+is a list starting with the program's executable file name, followed
+by strings to give to program as arguments.
+
+@item :coding @var{coding}
+If @var{coding} is a symbol, it specifies the coding system to be
+used for both reading and writing of data from and to the
+connection. If @var{coding} is a cons cell
+@w{@code{(@var{decoding} . @var{encoding})}}, then @var{decoding}
+will be used for reading and @var{encoding} for writing.
+
+If @var{coding} is @code{nil}, the default rules for finding the
+coding system will apply. @xref{Default Coding Systems}.
+
+@item :connection-type @var{TYPE}
+Initialize the type of device used to communicate with the subprocess.
+Possible values are @code{pty} to use a pty, @code{pipe} to use a
+pipe, or @code{nil} to use the default derived from the value of
+the @code{process-connection-type} variable.
+
+@item :noquery @var{query-flag}
+Initialize the process query flag to @var{query-flag}.
+@xref{Query Before Exit}.
+
+@item :stop @var{stopped}
+If @var{stopped} is non-@code{nil}, start the process in the
+stopped state.
+
+@item :filter @var{filter}
+Initialize the process filter to @var{filter}. If not specified, a
+default filter will be provided. @xref{Filter Functions}.
+
+@item :sentinel @var{sentinel}
+Initialize the process sentinel to @var{sentinel}. If not specified,
+a default sentinel will be used. @xref{Sentinels}.
+
+@item :stderr @var{stderr}
+Associate @var{stderr} with the standard error of the process.
+@var{stderr} is either a buffer or a pipe process created with
+@code{make-pipe-process}.
+@end table
+
+The original argument list, modified with the actual connection
+information, is available via the @code{process-contact} function.
+@end defun
+
+@defun make-pipe-process &rest args
+This function creates a bidirectional pipe which can be attached to a
+child process (currently only useful with the @code{:stderr} keyword
+of @code{make-process}).
+
+The arguments @var{args} are a list of keyword/argument pairs.
+Omitting a keyword is always equivalent to specifying it with value
+@code{nil}, except for @code{:coding}.
+Here are the meaningful keywords:
+
+@table @asis
+@item :name @var{name}
+Use the string @var{name} as the process name. It is modified if
+necessary to make it unique.
+
+@item :buffer @var{buffer}
+Use @var{buffer} as the process buffer.
+
+@item :coding @var{coding}
+If @var{coding} is a symbol, it specifies the coding system to be
+used for both reading and writing of data from and to the
+connection. If @var{coding} is a cons cell
+@w{@code{(@var{decoding} . @var{encoding})}}, then @var{decoding}
+will be used for reading and @var{encoding} for writing.
+
+If @var{coding} is @code{nil}, the default rules for finding the
+coding system will apply. @xref{Default Coding Systems}.
+
+@item :noquery @var{query-flag}
+Initialize the process query flag to @var{query-flag}.
+@xref{Query Before Exit}.
+
+@item :stop @var{stopped}
+If @var{stopped} is non-@code{nil}, start the process in the
+stopped state.
+
+@item :filter @var{filter}
+Initialize the process filter to @var{filter}. If not specified, a
+default filter will be provided. @xref{Filter Functions}.
+
+@item :sentinel @var{sentinel}
+Initialize the process sentinel to @var{sentinel}. If not specified,
+a default sentinel will be used. @xref{Sentinels}.
+@end table
+
+The original argument list, modified with the actual connection
+information, is available via the @code{process-contact} function.
+@end defun
+
@node Deleting Processes
@section Deleting Processes
@cindex deleting processes
@node Process Information
@section Process Information
+@cindex process information
Several functions return information about processes.
@item :buffer
The associated value is the process buffer.
@item :filter
-The associated value is the process filter function.
+The associated value is the process filter function. @xref{Filter
+Functions}.
@item :sentinel
-The associated value is the process sentinel function.
+The associated value is the process sentinel function. @xref{Sentinels}.
@item :remote
In a connection, the address in internal format of the remote peer.
@item :local
Asynchronous subprocesses receive input when it is sent to them by
Emacs, which is done with the functions in this section. You must
specify the process to send input to, and the input data to send. The
-data appears on the ``standard input'' of the subprocess.
+data appears on the standard input of the subprocess.
@c FIXME which?
Some operating systems have limited space for buffered input in a
@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 @key{DEL} on
+signal @code{SIGINT}. Outside of Emacs, typing the interrupt
+character (normally @kbd{C-c} on some systems, and @key{DEL} on
others) sends this signal. When the argument @var{current-group} is
-non-@code{nil}, you can think of this function as ``typing @kbd{C-c}''
+non-@code{nil}, you can think of this function as typing @kbd{C-c}
on the terminal by which Emacs talks to the subprocess.
@end defun
@defun quit-process &optional process current-group
This function sends the signal @code{SIGQUIT} to the process
-@var{process}. This signal is the one sent by the ``quit
-@c FIXME? Never heard of C-b being used for this. In readline, e.g.,
-@c bash, that is backward-word.
-character'' (usually @kbd{C-b} or @kbd{C-\}) when you are not inside
+@var{process}. This signal is the one sent by the quit
+character (usually @kbd{C-\}) when you are not inside
Emacs.
@end defun
signal @code{SIGTSTP}. Use @code{continue-process} to resume its
execution.
-Outside of Emacs, on systems with job control, the ``stop character''
+Outside of Emacs, on systems with job control, the stop character
(usually @kbd{C-z}) normally sends this signal. When
@var{current-group} is non-@code{nil}, you can think of this function as
-``typing @kbd{C-z}'' on the terminal Emacs uses to communicate with the
+typing @kbd{C-z} on the terminal Emacs uses to communicate with the
subprocess.
@end defun
@cindex filter function
@cindex process filter
+@cindex default filter function of a process
A process @dfn{filter function} is a function that receives the
standard output from the associated process. @emph{All} output from
that process is passed to the filter. The default filter simply
arguments: the process for which the event occurred, and a string
describing the type of event.
+@cindex default sentinel function of a process
+ If no sentinel function was specified for a process, it will use the
+default sentinel function, which inserts a message in the process's
+buffer with the process name and the string describing the event.
+
The string describing the event looks like one of the following:
-@c FIXME? Also "killed\n" - see example below?
@itemize @bullet
@item
@code{"finished\n"}.
@item
-@code{"exited abnormally with code @var{exitcode}\n"}.
+@code{"deleted\n"}.
+
+@item
+@code{"exited abnormally with code @var{exitcode} (core dumped)\n"}.
+The ``core dumped'' part is optional, and only appears if the process
+dumped core.
+
+@item
+@code{"failed with code @var{fail-code}\n"}.
+
+@item
+@code{"@var{signal-description} (core dumped)\n"}. The
+@var{signal-description} is a system-dependent textual description of
+a signal, e.g., @code{"killed"} for @code{SIGKILL}. The ``core
+dumped'' part is optional, and only appears if the process dumped
+core.
+
+@item
+@code{"open from @var{host-name}\n"}.
@item
-@code{"@var{name-of-signal}\n"}.
+@code{"open\n"}.
@item
-@code{"@var{name-of-signal} (core dumped)\n"}.
+@code{"connection broken by remote peer\n"}.
@end itemize
A sentinel runs only while Emacs is waiting (e.g., for terminal
@group
(defun msg-me (process event)
(princ
- (format "Process: %s had the event `%s'" process event)))
+ (format "Process: %s had the event '%s'" process event)))
(set-process-sentinel (get-process "shell") 'msg-me)
@result{} msg-me
@end group
@group
(kill-process (get-process "shell"))
- @print{} Process: #<process shell> had the event `killed'
+ @print{} Process: #<process shell> had the event 'killed'
@result{} #<process shell>
@end group
@end smallexample
@item "T"
stopped, e.g., by a job control signal
@item "Z"
-``zombie'': a process that terminated, but was not reaped by its parent
+zombie: a process that terminated, but was not reaped by its parent
@end table
@noindent
@cindex @acronym{STARTTLS} network connections
Emacs can create encrypted network connections, using either built-in
or external support. The built-in support uses the GnuTLS
-(``Transport Layer Security'') library; see
+Transport Layer Security Library; see
@uref{http://www.gnu.org/software/gnutls/, the GnuTLS project page}.
If your Emacs was compiled with GnuTLS support, the function
@code{gnutls-available-p} is defined and returns non-@code{nil}. For
An ordinary, unencrypted connection.
@item tls
@itemx ssl
-A @acronym{TLS} (``Transport Layer Security'') connection.
+A @acronym{TLS} (Transport Layer Security) connection.
@item nil
@itemx network
Start with a plain connection, and if parameters @samp{:success}
@item :type @var{type}
Specify the communication type. A value of @code{nil} specifies a
stream connection (the default); @code{datagram} specifies a datagram
-connection; @code{seqpacket} specifies a ``sequenced packet stream''
+connection; @code{seqpacket} specifies a sequenced packet stream
connection. Both connections and servers can be of these types.
@item :server @var{server-flag}
in the local address space.
@item
-An ``unsupported family'' address is represented by a cons
+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 one element
per address data byte. Do not rely on this format in portable code,
@item :stop @var{stopped}
If @var{stopped} is non-@code{nil}, start the network connection or
-server in the ``stopped'' state.
+server in the stopped state.
@item :buffer @var{buffer}
Use @var{buffer} as the process buffer.
Before Exit}. The flags defaults to @code{nil} if unspecified.
@item :stop @var{bool}
-Start process in the ``stopped'' state if @var{bool} is
+Start process in the stopped state if @var{bool} is
non-@code{nil}. In the stopped state, a serial process does not
accept incoming data, but you can send outgoing data. The stopped
state is cleared by @code{continue-process} and set by
@dfn{fields}. This specification controls the length of each field to be
processed, and how to pack or unpack it. We normally keep bindat specs
in variables whose names end in @samp{-bindat-spec}; that kind of name
-is automatically recognized as ``risky''.
+is automatically recognized as risky.
@cindex endianness
@cindex big endian
A field's @dfn{type} describes the size (in bytes) of the object
that the field represents and, in the case of multibyte fields, how
the bytes are ordered within the field. The two possible orderings
-are ``big endian'' (also known as ``network byte ordering'') and
-``little endian''. For instance, the number @code{#x23cd} (decimal
+are @dfn{big endian} (also known as ``network byte ordering'') and
+@dfn{little endian}. For instance, the number @code{#x23cd} (decimal
9165) in big endian would be the two bytes @code{#x23} @code{#xcd};
and in little endian, @code{#xcd} @code{#x23}. Here are the possible
type values: