Each terminal has a list of associated parameters. These terminal parameters are mostly a convenient way of storage for terminal-local variables, but some terminal parameters have a special meaning.
This section describes functions to read and change the parameter values
of a terminal. They all accept as their argument either a terminal or
a frame; the latter means use that frame’s terminal. An argument of
nil means the selected frame’s terminal.
This function returns an alist listing all the parameters of terminal and their values.
This function returns the value of the parameter parameter (a
symbol) of terminal. If terminal has no setting for
parameter, this function returns nil.
This function sets the parameter parameter of terminal to the specified value, and returns the previous value of that parameter.
Here’s a list of a few terminal parameters that have a special meaning:
background-modeThe classification of the terminal’s background color, either
light or dark.
normal-erase-is-backspaceValue is either 1 or 0, depending on whether
normal-erase-is-backspace-mode is turned on or off on this
terminal. See DEL Does Not Delete in The Emacs Manual.
terminal-inittedAfter the terminal is initialized, this is set to the terminal-specific initialization function.
tty-mode-set-stringsWhen present, a list of strings containing escape sequences that Emacs
will output while configuring a tty for rendering. Emacs emits these
strings only when configuring a terminal: if you want to enable a mode
on a terminal that is already active (for example, while in
tty-setup-hook), explicitly output the necessary escape
sequence using send-string-to-terminal in addition to adding
the sequence to tty-mode-set-strings.
tty-mode-reset-stringsWhen present, a list of strings that undo the effects of the strings
in tty-mode-set-strings. Emacs emits these strings when
exiting, deleting a terminal, or suspending itself.