send

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



________________________________________________________________________________

NAME
       send - Execute a command in a different application

SYNOPSIS
       send ?options? app cmd ?arg arg ...?
________________________________________________________________________________

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
              containing 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 incoming
       send requests anymore,  nor will it be able to issue outgoing requests.
       Communication can be reenabled by invoking the tk appname command.

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 connect 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 connect to your server unless they use
       some other form of authorization such as that provide by xauth.  Under
       Windows, send is currently disabled.  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)