- NAME
- console — Control the console on systems without a real
console
- SYNOPSIS
- DESCRIPTION
- console
eval script
- console
hide
- console
show
- console
title ?string?
- ACCESS TO THE
MAIN INTERPRETER
- consoleinterp eval script
- consoleinterp record script
- ADDITIONAL TRAP
CALLS
- DEFAULT
BINDINGS
- EXAMPLE
- SEE
ALSO
- KEYWORDS
console — Control the console on systems without a real console
console subcommand ?arg ...?
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.
- 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
deiconifying 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
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.
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.)
The default script creates a console window (implemented using a
text widget) that has the following behaviour:
- Pressing the tab key inserts a TAB character (as
defined by the Tcl \t escape.)
- 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.
- 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.)
- 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.)
- 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.)
- Pressing either Control+E or the end key causes the
cursor to go to the end of the line.
- Pressing either Control+P or the up key causes the
previous entry in the command history to be selected.
- Pressing either Control+N or the down key causes the
next entry in the command history to be selected.
- 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.
- Pressing either Control+F or the right key causes
the cursor to move one character forward.
- 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.
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}
destroy,
fconfigure, history, interp, puts,
text, wm
console, interpreter, window, interactive, output channels
Copyright © 2001 Donal K. Fellows