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



NAME
       send - Execute a command in a different application

SYNOPSIS
       (send ?options? app cmd ?arg arg ...?)
       (inhibit-send)


DESCRIPTION
       This procedure arranges for cmd (and args) to be executed in the
       application named by app. It returns the result (converted to a string)
       that procedure 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 procedure to be executed is contained entirely within the cmd
       argument.  If one or more args are present, they are concatenated to
       form the procedure to be executed, just as for the eval procedure.

       If the initial arguments of the procedure begin with ``-'' they are
       treated as options.  The following options are currently defined:

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

       :displayof widget-name
              Specifies that the target application's main window is on the
              display of the window given by widget-name, 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 procedure.


DISABLING SENDS
       The send procedure can be removed from an application by calling the
       inhibit-send procedure.  If the send procedure is removed 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 procedure.


SECURITY
       The send procedure 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 STk 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.


SEE ALSO
       tk



STk                                   3.1                              send(n)
