359 lines
14 KiB
Racket
359 lines
14 KiB
Racket
#lang scribble/doc
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@(require "mz.ss"
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(for-label scheme/system))
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@title[#:tag "subprocess"]{Processes}
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@defproc*[([(subprocess [stdout (or/c (and/c output-port? file-stream-port?) #f)]
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[stdin (or/c (and/c input-port? file-stream-port?) #f)]
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[stderr (or/c (and/c output-port? file-stream-port?) #f)]
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[command path-string?]
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[arg string?] ...)
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(values subprocess?
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(or/c (and/c input-port? file-stream-port?) #f)
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(or/c (and/c output-port? file-stream-port?) #f)
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(or/c (and/c input-port? file-stream-port?) #f))]
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[(subprocess [stdout (or/c (and/c output-port? file-stream-port?) #f)]
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[stdin (or/c (and/c input-port? file-stream-port?) #f)]
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[stderr (or/c (and/c output-port? file-stream-port?) #f)]
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[command path-string?]
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[exact 'exact]
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[arg string?])
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(values subprocess?
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(or/c (and/c input-port? file-stream-port?) #f)
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(or/c (and/c output-port? file-stream-port?) #f)
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(or/c (and/c input-port? file-stream-port?) #f))])]{
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Creates a new process in the underlying operating system to execute
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@scheme[command] asynchronously. See also @scheme[system] and
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@scheme[process] from @schememodname[scheme/system].
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The @scheme[command] argument is a path to a program executable, and
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the @scheme[arg]s are command-line arguments for the program. Under
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Unix and Mac OS X, command-line arguments are passed as byte strings
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using the current locale's encoding (see @secref["encodings"]).
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Under Windows, the first @scheme[arg] can be replaced with
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@indexed-scheme['exact], which triggers a Windows-specific behavior:
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the sole @scheme[arg] is used exactly as the command-line for the
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subprocess. Otherwise, under Windows, a command-line string is
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constructed from @scheme[command] and @scheme[arg] so that a typical
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Windows console application can parse it back to an array of
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arguments. If @scheme['exact] is provided on a non-Windows platform,
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the @exnraise[exn:fail:contract].
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@margin-note{For information on the Windows command-line conventions,
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search for ``command line parsing'' at
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@tt{http://msdn.microsoft.com/}.}
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Unless it is @scheme[#f], @scheme[stdout] is used for the launched
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process's standard output, @scheme[stdin] is used for the process's
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standard input, and @scheme[stderr] is used for the process's standard
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error. All provided ports must be file-stream ports. Any of the ports
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can be @scheme[#f], in which case a system pipe is created and
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returned by @scheme[subprocess]. For each port that is provided, no
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pipe is created and the corresponding returned value is @scheme[#f].
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The @scheme[subprocess] procedure returns four values:
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@itemize{
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@item{a subprocess value representing the created process;}
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@item{an input port piped from the process's standard output, or
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@scheme[#f] if @scheme[stdout-output-port] was a port;}
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@item{an output port piped to the process standard input, or
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@scheme[#f] if @scheme[stdin-input-port] was a port;}
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@item{an input port piped from the process's standard error, or
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@scheme[#f] if @scheme[stderr-output-port] was a port.}
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}
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@bold{Important:} All ports returned from @scheme[subprocess] must be
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explicitly closed with @scheme[close-input-port] or
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@scheme[close-output-port].
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The returned ports are @tech{file-stream ports} (see
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@secref["file-ports"]), and they are placed into the management of
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the current custodian (see @secref["custodians"]). The
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@exnraise[exn:fail] when a low-level error prevents the spawning of a
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process or the creation of operating system pipes for process
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communication.}
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@defproc[(subprocess-wait [subproc subprocess?]) void?]{
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Blocks until the process represented by @scheme[subproc] terminates.}
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@defproc[(subprocess-status [subproc subprocess?])
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(or/c 'running
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exact-nonnegative-integer?)]{
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Returns @indexed-scheme['running] if the process represented by
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@scheme[subproc] is still running, or its exit code otherwise. The
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exit code is an exact integer, and @scheme[0] typically indicates
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success. If the process terminated due to a fault or signal, the exit
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code is non-zero.}
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@defproc[(subprocess-kill [subproc subprocess?][force? any/c]) void?]{
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Terminates the subprocess represented by @scheme[subproc] if
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@scheme[force?] is true and if the process still running. If an error
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occurs during termination, the @exnraise[exn:fail].
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If @scheme[force?] is @scheme[#f] under @|AllUnix|, the subprocess is
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sent an interrupt signal instead of a kill signal (and the subprocess
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might handle the signal without terminating). Under Windows, no action
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is taken when @scheme[force?] is @scheme[#f].}
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@defproc[(subprocess-pid [subproce subprocess?]) exact-nonnegative-integer?]{
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Returns the operating system's numerical ID (if any) for the process
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represented by @scheme[subproc], valid only as long as the process is
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running.}
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@defproc[(subprocess? [v any/c]) boolean?]{
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Returns @scheme[#t] if @scheme[v] is a subprocess value, @scheme[#f]
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otherwise.}
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@defproc[(shell-execute [verb (or/c string? #f)]
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[target string?][parameters string?][dir path-string?][show-mode symbol?])
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#f]
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@index['("ShellExecute")]{Performs} the action specified by @scheme[verb]
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on @scheme[target] in Windows. For platforms other than Windows, the
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@exnraise[exn:fail:unsupported].
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For example,
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@schemeblock[
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(shell-execute #f "http://www.plt-scheme.org" ""
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(current-directory) 'sw_shownormal)
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]
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Opens the PLT Scheme home page in a browser window.
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The @scheme[verb] can be @scheme[#f], in which case the operating
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system will use a default verb. Common verbs include @scheme["open"],
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@scheme["edit"], @scheme["find"], @scheme["explore"], and
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@scheme["print"].
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The @scheme[target] is the target for the action, usually a filename
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path. The file could be executable, or it could be a file with a
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recognized extension that can be handled by an installed application.
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The @scheme[parameters] argument is passed on to the system to perform
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the action. For example, in the case of opening an executable, the
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@scheme[parameters] is used as the command line (after the executable
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name).
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The @scheme[dir] is used as the current directory when performing the
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action.
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The @scheme[show-mode] sets the display mode for a Window affected by
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the action. It must be one of the following symbols; the description
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of each symbol's meaning is taken from the Windows API documentation.
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@itemize{
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@item{@indexed-scheme['sw_hide] or @indexed-scheme['SW_HIDE] ---
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Hides the window and activates another window.}
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@item{@indexed-scheme['sw_maximize] or @indexed-scheme['SW_MAXIMIZE]
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--- Maximizes the window.}
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@item{@indexed-scheme['sw_minimize] or @indexed-scheme['SW_MINIMIZE]
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--- Minimizes the window and activates the next top-level window in
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the z-order.}
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@item{@indexed-scheme['sw_restore] or @indexed-scheme['SW_RESTORE]
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--- Activates and displays the window. If the window is minimized or
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maximized, Windows restores it to its original size and position.}
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@item{@indexed-scheme['sw_show] or @indexed-scheme['SW_SHOW] ---
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Activates the window and displays it in its current size and
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position.}
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@item{@indexed-scheme['sw_showdefault] or
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@indexed-scheme['SW_SHOWDEFAULT] --- Uses a default.}
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@item{@indexed-scheme['sw_showmaximized] or
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@indexed-scheme['SW_SHOWMAXIMIZED] --- Activates the window and
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displays it as a maximized window.}
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@item{@indexed-scheme['sw_showminimized] or
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@indexed-scheme['SW_SHOWMINIMIZED] --- Activates the window and
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displays it as a minimized window.}
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@item{@indexed-scheme['sw_showminnoactive] or
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@indexed-scheme['SW_SHOWMINNOACTIVE] --- Displays the window as a
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minimized window. The active window remains active.}
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@item{@indexed-scheme['sw_showna] or @indexed-scheme['SW_SHOWNA] ---
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Displays the window in its current state. The active window remains
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active.}
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@item{@indexed-scheme['sw_shownoactivate] or
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@indexed-scheme['SW_SHOWNOACTIVATE] --- Displays a window in its most
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recent size and position. The active window remains active.}
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@item{@indexed-scheme['sw_shownormal] or
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@indexed-scheme['SW_SHOWNORMAL] --- Activates and displays a
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window. If the window is minimized or maximized, Windows restores it
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to its original size and position.}
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}
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If the action fails, the @exnraise[exn:fail]. If the action succeeds,
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the result is @scheme[#f].
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In future versions of Scheme, the result may be a subprocess value if
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the operating system did returns a process handle (but if a subprocess
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value is returned, its process ID will be @scheme[0] instead of the
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real process ID).
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@; ----------------------------------------------------------------------
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@section{Simple Subprocesses}
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@note-lib-only[scheme/system]
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@defproc[(system [command string?]) boolean?]{
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Executes a Unix, Mac OS X, or Windows shell command synchronously
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(i.e., the call to @scheme[system] does not return until the
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subprocess has ended). The @scheme[command] argument is a string
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containing no nul characters. If the command succeeds, the return
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value is @scheme[#t], @scheme[#f] otherwise.}
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@defproc*[([(system* [command path-string?][arg string?] ...) boolean?]
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[(system* [command path-string?][exact 'exact][arg string?]) boolean?])]{
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Like @scheme[system], except that @scheme[command] is a filename that
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is executed directly (instead of through a shell command), and the
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@scheme[arg]s are the arguments. The executed file is passed the
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specified string arguments (which must contain no nul
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characters).
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Under Windows, the first argument after @scheme[command] can be
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@scheme['exact], and the final @scheme[arg] is a complete command
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line. See @scheme[subprocess] for details.}
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@defproc[(system/exit-code [command string?]) (integer-in 0 255)]{
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Like @scheme[system], except that the result is the exit code returned
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by the subprocess. A @scheme[0] result normally indicates success.}
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@defproc*[([(system*/exit-code [command path-string?][arg string?] ...) (integer-in 0 255)]
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[(system*/exit-code [command path-string?][exact 'exact][arg string?]) (integer-in 0 255)])]{
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Like @scheme[system*], but returns the exit code like
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@scheme[system/exit-code].}
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@defproc[(process [command string?])
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(list input-port?
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output-port?
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exact-nonnegative-integer?
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input-port?
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((or/c 'status 'wait 'interrupt 'kill) . -> . any))]{
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Executes a shell command asynchronously. The result is a list of five values:
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@itemize{
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@item{an input port piped from the subprocess's standard output,}
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@item{an output port piped to the subprocess standard input,}
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@item{the system process id of the subprocess,}
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@item{an input port piped from the subprocess's standard
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error, and}
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@item{a procedure of one argument, either @scheme['status],
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@scheme['wait], @scheme['interrupt], or @scheme['kill]:
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@itemize{
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@item{@scheme['status] returns the status of the subprocess as one
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of @scheme['running], @scheme['done-ok], or
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@scheme['done-error].}
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@item{@scheme['exit-code] returns the integer exit code of the
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subprocess or @scheme[#f] if it is still running.}
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@item{@scheme['wait] blocks execution in the current thread until
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the subprocess has completed.}
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@item{@scheme['interrupt] sends the subprocess an interrupt signal
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under @|AllUnix|, and takes no action under Windows. The result is
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@|void-const|.}
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@item{@scheme['kill] terminates the subprocess and returns
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@|void-const|. Note that the immediate process created by
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@scheme[process] is a shell process that may run another program;
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terminating the shell process may not terminate processes that
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the shell starts, particularly under Windows.}
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}}
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}
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@bold{Important:} All three ports returned from @scheme[process] must
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be explicitly closed with @scheme[close-input-port] or
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@scheme[close-output-port].}
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@defproc*[([(process* [command path-string?][arg string?] ...) list?]
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[(process* [command path-string?][exact 'exact][arg string?]) list?])]{
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Like @scheme[process], except that @scheme[command] is a filename that
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is executed directly, and the @scheme[arg]s are the arguments. Under
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Windows, as for @scheme[system*], the first @scheme[arg] can be
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replaced with @scheme['exact].}
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@defproc[(process/ports [out (or/c #f output-port?)]
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[in (or/c #f input-port?)]
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[error-out (or/c #f output-port?)]
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[command string?])
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list?]{
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Like @scheme[process], except that @scheme[out] is used for the
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process's standard output, @scheme[in] is used for the process's
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standard input, and @scheme[error-out] is used for the process's
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standard error. Any of the ports can be @scheme[#f], in which case a
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system pipe is created and returned, as in @scheme[process]. For each
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port that is provided, no pipe is created, and the corresponding value
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in the returned list is @scheme[#f].}
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@defproc*[([(process*/ports [out (or/c #f output-port?)]
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[in (or/c #f input-port?)]
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[error-out (or/c #f output-port?)]
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[command path-string?]
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[arg string?] ...)
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list?]
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[(process*/ports [out (or/c #f output-port?)]
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[in (or/c #f input-port?)]
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[error-out (or/c #f output-port?)]
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[command path-string?]
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[exact 'exact]
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[arg string?])
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list?])]{
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Like @scheme[process*], but with the port handling of
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@scheme[process/ports].}
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