update(n)		     Ck Built-In Commands		     update(n)



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NAME
       update - Process pending events and/or when-idle handlers

SYNOPSIS
       update ?idletasks|screen?
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DESCRIPTION
       This  command  is  used	to  bring the entire application world ``up to
       date.''	It flushes all pending output to the display,  waits  for  the
       server  to process that output and return errors or events, handles all
       pending events of any sort (including when-idle handlers), and  repeats
       this  set  of  operations until there are no pending events, no pending
       when-idle handlers, no pending output to the server, and no  operations
       still outstanding at the server.

       If  the	idletasks  keyword is specified as an argument to the command,
       then no new events or errors are processed;  only when-idle idlers  are
       invoked.	  This	causes	operations that are normally deferred, such as
       display updates and window layout calculations, to be performed immedi-
       ately.

       The  update  idletasks  command is useful in scripts where changes have
       been made to the application's state and you want those changes to  ap-
       pear  on the display immediately, rather than waiting for the script to
       complete.  Most display updates are performed as idle handlers, so  up-
       date  idletasks	will cause them to run.	 However, there are some kinds
       of updates that only happen in response to events, such as those	 trig-
       gered  by  window  size changes; these updates will not occur in update
       idletasks.

       If the screen keyword is specified as an argument to the command,  then
       the  entire screen is repainted from scratch without handling any other
       events. This is useful if the terminal's screen has been garbled by an-
       other process.

       The  update  command with no options is useful in scripts where you are
       performing a long-running computation but you still want	 the  applica-
       tion  to respond to user interactions;  if you occasionally call update
       then user input will be processed during the next call to update.


KEYWORDS
       event, flush, handler, idle, update



Ck				      8.0			     update(n)
