send(n) 						       Tk Built-In Commands							   send(n)

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NAME

       send - Execute a command in a different application

SYNOPSIS

       send ?options? app cmd ?arg arg ...?
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DESCRIPTION

       This  command arranges for cmd (and args) to be executed in the application named by app.  It returns the result or error from that command
       execution.  App may be the name of any application whose main window is on the display containing the sender's main window;  it need not be
       within  the  same process.  If no arg arguments are present, then the command to be executed is contained entirely within the cmd argument.
       If one or more args are present, they are concatenated to form the command to be executed, just as for the eval command.

       If the initial arguments of the command begin with "-" they are treated as options.  The following options are currently defined:

       -async Requests asynchronous invocation.  In this case the send command will complete immediately without waiting for cmd  to  complete	in
	      the  target  application;  no result will be available and errors in the sent command will be ignored.  If the target application is
	      in the same process as the sending application then the -async option is ignored.

       -displayof pathName
	      Specifies that the target application's main window is on the display of the window given by pathName, instead of the  display  con-
	      taining the application's main window.

       --     Serves no purpose except to terminate the list of options.  This option is needed only if app could contain a leading "-" character.

APPLICATION NAMES

       The  name of an application is set initially from the name of the program or script that created the application.  You can query and change
       the name of an application with the tk appname command.

DISABLING SENDS

       If the send command is removed from an application (e.g.  with the command rename send {}) then the application will not respond to  incom-
       ing send requests anymore,  nor will it be able to issue outgoing requests.  Communication can be reenabled by invoking the tk appname com-
       mand.

SECURITY

       The send command is potentially a serious security loophole. On Unix, any application that can connect to your X server can send scripts to
       your  applications.   These  incoming scripts can use Tcl to read and write your files and invoke subprocesses under your name.	Host-based
       access control such as that provided by xhost is particularly insecure, since it allows anyone with an account on particular hosts to  con-
       nect  to  your server, and if disabled it allows anyone anywhere to connect to your server.  In order to provide at least a small amount of
       security, Tk checks the access control being used by the server and rejects incoming sends unless (a) xhost-style access control is enabled
       (i.e.  only  certain hosts can establish connections) and (b) the list of enabled hosts is empty.  This means that applications cannot con-
       nect to your server unless they use some other form of authorization such as that provide by xauth.  Under Windows, send is currently  dis-
       abled.  Most of the functionality is provided by the dde command instead.

EXAMPLE

       This script fragment can be used to make an application that only runs once on a particular display.
	      if {[tk appname FoobarApp] ne "FoobarApp"} {
		  send -async FoobarApp RemoteStart $argv
		  exit
	      }
	      # The command that will be called remotely, which raises
	      # the application main window and opens the requested files
	      proc RemoteStart args {
		  raise .
		  foreach filename $args {
		      OpenFile $filename
		  }
	      }

KEYWORDS

       application, dde, name, remote execution, security, send

Tk									4.0								   send(n)