How to configure terminal to change behaviour on calling executable...

[mgajda]

It would be nice to change behaviour when a different executable is called:

1. When ssh is called to another machine, add options for SSH out-of-band commands (copy file, open remote port etc.)
2. When vim is called, add an option to open the same local file in another window, or show URL of the file.
3. When launching a command supporting xterm-256color (like Vim, or CLI output colorizer), switch TERMINFO to xterm-256color or better.
4. When serial console is open (/dev/ttyUSB*), limit TERMINFO to barebones.

Many of the shells and commands simply set terminal name using special characters, so one could add a hook
that recognizes the name by a regex.
That would be a hook from Name -> ... -> IO Terminal.

Some other shells use a command sequence to find terminal name, we could try to react to this detection, and leave it to the user to choose TERMINFO and switch it.

Related to #215

[cdepillabout]

When ssh is called to another machine, add options for SSH out-of-band commands (copy file, open remote port etc.)

Let me make sure I understand what you're suggesting. So, when you run Termonad, initially bash is run, and then within bash, if you run the ssh command, you'd like additional MenuBar options to be available to run SSH out-of-band commands?

That would be really neat.

One problem is that Termonad is just using VTE for the actual terminal emulator, so VTE may not expose all the functionality that would be needed to implement this. Here's the code in Termonad related to VTE:

https://github.com/cdepillabout/termonad/blob/e47d4b2cfe87849c03f327a4befb962dc5614b43/src/Termonad/Term.hs

It is mostly driven by this function:

termonad/src/Termonad/Term.hs

Lines 428 to 485 in e47d4b2

	-- | Create a new 'TMTerm', setting it up and adding it to the GTKNotebook.
	createTerm
	:: (TMState -> EventKey -> IO Bool)
	-- ^ Funtion for handling key presses on the terminal.
	-> TMState
	-> IO TMTerm
	createTerm handleKeyPress mvarTMState = do
	-- Check preconditions
	assertInvariantTMState mvarTMState
	-- Read needed data in TMVar
	TMState{tmStateAppWin, tmStateFontDesc, tmStateConfig, tmStateNotebook=currNote} <-
	readMVar mvarTMState
	-- Create a new terminal and launch a shell in it
	vteTerm <- createAndInitVteTerm tmStateFontDesc (options tmStateConfig)
	maybeCurrDir <- getCWDFromFocusedTab currNote
	termShellPid <- launchShell vteTerm maybeCurrDir
	tmTerm <- newTMTerm vteTerm termShellPid
	-- Create the container add the VTE term in it
	scrolledWin <- createScrolledWin mvarTMState
	containerAdd scrolledWin vteTerm
	-- Create the GTK widget for the Notebook tab
	(tabLabelBox, tabLabel, tabCloseButton) <- createNotebookTabLabel
	-- Create notebook state
	let notebookTab = createTMNotebookTab tabLabel scrolledWin tmTerm
	-- Add the new notebooktab to the notebook.
	addPage mvarTMState notebookTab tabLabelBox
	-- Setup the initial label for the notebook tab. This needs to happen
	-- after we add the new page to the notebook, so that the page can get labelled
	-- appropriately.
	relabelTab (tmNotebook currNote) tabLabel scrolledWin vteTerm
	-- Connect callbacks
	void $ onButtonClicked tabCloseButton $ termClose notebookTab mvarTMState
	void $ onTerminalWindowTitleChanged vteTerm $ do
	TMState{tmStateNotebook} <- readMVar mvarTMState
	let notebook = tmNotebook tmStateNotebook
	relabelTab notebook tabLabel scrolledWin vteTerm
	void $ onWidgetKeyPressEvent vteTerm $ handleKeyPress mvarTMState
	void $ onWidgetKeyPressEvent scrolledWin $ handleKeyPress mvarTMState
	void $ onWidgetButtonPressEvent vteTerm $ handleMousePress vteTerm
	void $ onTerminalChildExited vteTerm $ \_ -> termExit notebookTab mvarTMState
	-- Put the keyboard focus on the term
	setFocusOn tmStateAppWin vteTerm
	-- Make sure the state is still right
	assertInvariantTMState mvarTMState
	-- Run user-defined hooks for modifying the newly-created VTE Terminal.
	createTermHook (hooks tmStateConfig) mvarTMState vteTerm
	pure tmTerm

Here's the Haddocks for the VTE-related functionality:

https://hackage.haskell.org/package/gi-vte-2.91.29/docs/GI-Vte-Objects-Terminal.html

VTE / Termonad definitely has knowledge of the shell you run initially (bash), but I'm not sure how much knowledge they have of the commands you're running within bash. If you want to look through these APIs and try to figure something out, I'd really appreciate a PR.

Many of the shells and commands simply set terminal name using special characters, so one could add a hook
that recognizes the name by a regex.

If I remember off the top of my head, there is some functionality in VTE to pick up on the ANSI escape sequences to set window titles, but I don't quite remember how that works without digging into the code, or if you'd be able to hook into that functionality.