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send(3tk) Tk Built-In Commands send(3tk) 


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



  

    4.0
    Tk