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console(3tk) Tk Built-In Commands console(3tk) 





NAME


console - Control the console on systems without a real
  console






SYNOPSIS


console subcommand ?arg ...?








DESCRIPTION


The console window is a replacement for a real console to allow
    input and output on the standard I/O channels on platforms that do not have
    a real console. It is implemented as a separate interpreter with the Tk
    toolkit loaded, and control over this interpreter is given through the
    console command. The behaviour of the console window is defined
    mainly through the contents of the console.tcl file in the Tk
    library. Except for TkAqua, this command is not available when Tk is loaded
    into a tclsh interpreter with “package require Tk”, as
    a conventional terminal is expected to be present in that case. In TkAqua,
    this command is disabled when there is a startup script and stdin is
    /dev/null (as is the case e.g. when a bundled application embedding
    Tk is started by the macOS Launcher). To enable the command in that case,
    define the environment variable TK_CONSOLE. This can be done by
    modifying the Info.plist file by adding the LSEnvironment key to the main
    dict and setting its value to be a dict with the key TK_CONSOLE.



  

  
Evaluate the script argument as a Tcl script in the console
      interpreter. The normal interpreter is accessed through the
      consoleinterp command in the console interpreter.

  

  
Hide the console window from view. Precisely equivalent to withdrawing the
      . window in the console interpreter.

  

  
Display the console window. Precisely equivalent to deiconifying the
      . window in the console interpreter.

  

  
Query or modify the title of the console window. If string is not
      specified, queries the title of the console window, and sets the title of
      the console window to string otherwise. Precisely equivalent to
      using the wm title command in the console interpreter.








ACCESS TO THE MAIN INTERPRETER


The consoleinterp command in the console interpreter allows
    scripts to be evaluated in the main interpreter. It supports two
    subcommands: eval and record.



  

  
Evaluates script as a Tcl script at the global level in the main
      interpreter.

  

  
Records and evaluates script as a Tcl script at the global level in
      the main interpreter as if script had been typed in at the
    console.








ADDITIONAL TRAP CALLS


There are several additional commands in the console interpreter
    that are called in response to activity in the main interpreter. These
    are documented here for completeness only; they form part of the
    internal implementation of the console and are likely to change or be
    modified without warning.


Output to the console from the main interpreter via the stdout and
    stderr channels is handled by invoking the tk::ConsoleOutput command
    in the console interpreter with two arguments. The first argument is the
    name of the channel being written to, and the second argument is the string
    being written to the channel (after encoding and end-of-line translation
    processing has been performed.)


When the . window of the main interpreter is destroyed, the
    tk::ConsoleExit command in the console interpreter is called
    (assuming the console interpreter has not already been deleted itself, that
    is.)






DEFAULT BINDINGS


The default script creates a console window (implemented using a
    text widget) that has the following behaviour:



  
[1]

  
Pressing the tab key inserts a TAB character (as defined by the Tcl \t
      escape.)

  
[2]

  
Pressing the return key causes the current line (if complete by the rules
      of info complete) to be passed to the main interpreter for
      evaluation.

  
[3]

  
Pressing the delete key deletes the selected text (if any text is
      selected) or the character to the right of the cursor (if not at the end
      of the line.)

  
[4]

  
Pressing the backspace key deletes the selected text (if any text is
      selected) or the character to the left of the cursor (of not at the start
      of the line.)

  
[5]

  
Pressing either Control+A or the home key causes the cursor to go to the
      start of the line (but after the prompt, if a prompt is present on the
      line.)

  
[6]

  
Pressing either Control+E or the end key causes the cursor to go to the
      end of the line.

  
[7]

  
Pressing either Control+P or the up key causes the previous entry in the
      command history to be selected.

  
[8]

  
Pressing either Control+N or the down key causes the next entry in the
      command history to be selected.

  
[9]

  
Pressing either Control+B or the left key causes the cursor to move one
      character backward as long as the cursor is not at the prompt.

  
[10]

  
Pressing either Control+F or the right key causes the cursor to move one
      character forward.

  
[11]

  
Pressing F9 rebuilds the console window by destroying all its children and
      reloading the Tcl script that defined the console's behaviour.




Most other behaviour is the same as a conventional text widget
    except for the way that the <<Cut>> event is handled
    identically to the <<Copy>> event.






EXAMPLE


Not all platforms have the console command, so debugging
    code often has the following code fragment in it so output produced by
    puts can be seen while during development:




catch {console show}








SEE ALSO


destroy(3tk), fconfigure(3tcl), history(3tcl), interp(3tcl),
    puts(3tcl), text(3tk), wm(3tk)






KEYWORDS


console, interpreter, window, interactive, output channels







  

    8.4
    Tk