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.  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, since 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.


KEYWORDS
     application, name, remote execution, security, send