This is the library that handles reading input when using an interactive shell, unless the --noediting option is given at shell invocation. Line is also used when using the-e option to the read builtin. By default, the line editing commands are similar to those of emacs. A vi-style line interface is also available. Line editing can be enabled at any time using the -o emacs or-o vi options to the set builtin (see SHELL BUILTIN below). To turn off line editing after the shell is running, use the +o emacs or +o vi options to the set builtin.
In this first edit is the insert mode. To switch to normal-ESC