console(n) Tk Built-In Commands console(n) ______________________________________________________________________________
NAME
console - Control the console on systems without a real console
SYNOPSIS
console subcommand ?arg ...?
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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 envi-
ronment 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.
console eval script
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.
console hide
Hide the console window from view. Precisely equivalent to
withdrawing the . window in the console interpreter.
console show
Display the console window. Precisely equivalent to deiconify-
ing the . window in the console interpreter.
console title ?string?
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 inter-
preter.
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.
consoleinterp eval script
Evaluates script as a Tcl script at the global level in the main
interpreter.
consoleinterp record script
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::Con-
soleExit 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(n), fconfigure(n), history(n), interp(n), puts(n), text(n),
wm(n)
KEYWORDS
console, interpreter, window, interactive, output channels
Tk 8.4 console(n)
tk 8.6.11 - Generated Fri Jan 22 13:16:11 CST 2021