exit(n) Tcl Built-In Commands exit(n)
__________________________________________________________________________________________________________________________________________________NAME
exit - End the application
SYNOPSIS
exit ?returnCode?
_________________________________________________________________DESCRIPTION
Terminate the process, returning returnCode to the system as the exit status. If returnCode isn't specified then it defaults to 0.
SEE ALSO
exec(n), tclvars(n)
KEYWORDS
exit, process
Tcl exit(n)
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Tcl_Exit(3) Tcl Library Procedures Tcl_Exit(3)__________________________________________________________________________________________________________________________________________________NAME
Tcl_Exit, Tcl_Finalize, Tcl_CreateExitHandler, Tcl_DeleteExitHandler, Tcl_ExitThread, Tcl_FinalizeThread, Tcl_CreateThreadExitHandler,
Tcl_DeleteThreadExitHandler, Tcl_SetExitProc - end the application or thread (and invoke exit handlers)
SYNOPSIS
#include <tcl.h>
Tcl_Exit(status)
Tcl_Finalize()
Tcl_CreateExitHandler(proc, clientData)
Tcl_DeleteExitHandler(proc, clientData)
Tcl_ExitThread(status)
Tcl_FinalizeThread()
Tcl_CreateThreadExitHandler(proc, clientData)
Tcl_DeleteThreadExitHandler(proc, clientData)
Tcl_ExitProc * |
Tcl_SetExitProc(proc) |
ARGUMENTS
int status (in) Provides information about why the application or thread exited. Exact meaning may be platform-spe-
cific. 0 usually means a normal exit, any nonzero value usually means that an error occurred.
Tcl_ExitProc *proc (in) Procedure to invoke before exiting application, or (for Tcl_SetExitProc) NULL to uninstall the cur-
rent application exit procedure.
ClientData clientData (in) Arbitrary one-word value to pass to proc.
_________________________________________________________________DESCRIPTION
The procedures described here provide a graceful mechanism to end the execution of a Tcl application. Exit handlers are invoked to cleanup
the application's state before ending the execution of Tcl code.
Invoke Tcl_Exit to end a Tcl application and to exit from this process. This procedure is invoked by the exit command, and can be invoked
anyplace else to terminate the application. No-one should ever invoke the exit system procedure directly; always invoke Tcl_Exit instead,
so that it can invoke exit handlers. Note that if other code invokes exit system procedure directly, or otherwise causes the application
to terminate without calling Tcl_Exit, the exit handlers will not be run. Tcl_Exit internally invokes the exit system call, thus it never
returns control to its caller. If an application exit handler has been installed (see Tcl_SetExitProc), that handler is invoked with an |
argument consisting of the exit status (cast to ClientData); the application exit handler should not return control to Tcl.
Tcl_Finalize is similar to Tcl_Exit except that it does not exit from the current process. It is useful for cleaning up when a process is
finished using Tcl but wishes to continue executing, and when Tcl is used in a dynamically loaded extension that is about to be unloaded.
On some systems Tcl is automatically notified when it is being unloaded, and it calls Tcl_Finalize internally; on these systems it not nec-
essary for the caller to explicitly call Tcl_Finalize. However, to ensure portability, your code should always invoke Tcl_Finalize when
Tcl is being unloaded, to ensure that the code will work on all platforms. Tcl_Finalize can be safely called more than once.
Tcl_ExitThread is used to terminate the current thread and invoke per-thread exit handlers. This finalization is done by Tcl_Final-
izeThread, which you can call if you just want to clean up per-thread state and invoke the thread exit handlers. Tcl_Finalize calls
Tcl_FinalizeThread for the current thread automatically.
Tcl_CreateExitHandler arranges for proc to be invoked by Tcl_Finalize and Tcl_Exit. Tcl_CreateThreadExitHandler arranges for proc to be
invoked by Tcl_FinalizeThread and Tcl_ExitThread. This provides a hook for cleanup operations such as flushing buffers and freeing global
memory. Proc should match the type Tcl_ExitProc:
typedef void Tcl_ExitProc(ClientData clientData);
The clientData parameter to proc is a copy of the clientData argument given to Tcl_CreateExitHandler or Tcl_CreateThreadExitHandler when
the callback was created. Typically, clientData points to a data structure containing application-specific information about what to do in
proc.
Tcl_DeleteExitHandler and Tcl_DeleteThreadExitHandler may be called to delete a previously-created exit handler. It removes the handler
indicated by proc and clientData so that no call to proc will be made. If no such handler exists then Tcl_DeleteExitHandler or
Tcl_DeleteThreadExitHandler does nothing.
Tcl_Finalize and Tcl_Exit execute all registered exit handlers, in reverse order from the order in which they were registered. This
matches the natural order in which extensions are loaded and unloaded; if extension A loads extension B, it usually unloads B before it
itself is unloaded. If extension A registers its exit handlers before loading extension B, this ensures that any exit handlers for B will
be executed before the exit handlers for A.
Tcl_Finalize and Tcl_Exit call Tcl_FinalizeThread and the thread exit handlers after the process-wide exit handlers. This is because
thread finalization shuts down the I/O channel system, so any attempt at I/O by the global exit handlers will vanish into the bitbucket.
Tcl_SetExitProc installs an application exit handler, returning the previously-installed application exit handler or NULL if no application |
handler was installed. If an application exit handler is installed, that exit handler takes over complete responsibility for finalization |
of Tcl's subsystems via Tcl_Finalize at an appropriate time. The argument passed to proc when it is invoked will be the exit status code |
(as passed to Tcl_Exit) cast to a ClientData value.
KEYWORDS
callback, cleanup, dynamic loading, end application, exit, unloading, thread
Tcl 8.5 Tcl_Exit(3)