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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 ...?
____________________________________________________________________________________________________________


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  outgo-ing outgoing
       ing 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 con-nect connect
       nect 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 pro-vided provided
       vided 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)