1send(n) Tk Built-In Commands send(n)
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8 send - Execute a command in a different application
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11 send ?options? app cmd ?arg arg ...?
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15 This command arranges for cmd (and args) to be executed in the applica‐
16 tion named by app. It returns the result or error from that command
17 execution. App may be the name of any application whose main window is
18 on the display containing the sender's main window; it need not be
19 within the same process. If no arg arguments are present, then the
20 command to be executed is contained entirely within the cmd argument.
21 If one or more args are present, they are concatenated to form the com‐
22 mand to be executed, just as for the eval command.
23 If the initial arguments of the command begin with “-” they are treated
25 as options. The following options are currently defined:
26 -async Requests asynchronous invocation. In this case the send command
28 will complete immediately without waiting for cmd to complete in
29 the target application; no result will be available and errors
30 in the sent command will be ignored. If the target application
31 is in the same process as the sending application then the
32 -async option is ignored.
33 -displayof pathName
35 Specifies that the target application's main window is on the
36 display of the window given by pathName, instead of the display
37 containing the application's main window.
38 -- Serves no purpose except to terminate the list of options. This
40 option is needed only if app could contain a leading “-” charac‐
41 ter.
42
44 The name of an application is set initially from the name of the pro‐
45 gram or script that created the application. You can query and change
46 the name of an application with the tk appname command.
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49 If the send command is removed from an application (e.g. with the com‐
50 mand rename send {}) then the application will not respond to incoming
51 send requests anymore, nor will it be able to issue outgoing requests.
52 Communication can be reenabled by invoking the tk appname command.
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55 The send command is potentially a serious security loophole. On Unix,
56 any application that can connect to your X server can send scripts to
57 your applications. These incoming scripts can use Tcl to read and
58 write your files and invoke subprocesses under your name. Host-based
59 access control such as that provided by xhost is particularly insecure,
60 since it allows anyone with an account on particular hosts to connect
61 to your server, and if disabled it allows anyone anywhere to connect to
62 your server. In order to provide at least a small amount of security,
63 Tk checks the access control being used by the server and rejects in‐
64 coming sends unless (a) xhost-style access control is enabled (i.e.
65 only certain hosts can establish connections) and (b) the list of en‐
66 abled hosts is empty. This means that applications cannot connect to
67 your server unless they use some other form of authorization such as
68 that provide by xauth. Under Windows, send is currently disabled.
69 Most of the functionality is provided by the dde command instead.
70
72 This script fragment can be used to make an application that only runs
73 once on a particular display.
74 if {[tk appname FoobarApp] ne "FoobarApp"} {
75 send -async FoobarApp RemoteStart $argv
76 exit
77 }
78 # The command that will be called remotely, which raises
79 # the application main window and opens the requested files
80 proc RemoteStart args {
81 raise .
82 foreach filename $args {
83 OpenFile $filename
84 }
85 }
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88 application, dde, name, remote execution, security, send
89Tk 4.0 send(n)