[6] Fish displays incremental suggestions as the user types, based on command history and the current directory.

This functions similarly to Bash's Ctrl+R history search, but is always on, giving the user continuous feedback while typing commands.

Subshells are child programs that run a few commands in order to perform a task, then exit back to the parent shell.

This implementation detail typically has the side effect that any state changes made in the subshell, such as variable assignments, do not propagate to the main shell.

The variable value is remembered across logouts and reboots, and updates are immediately propagated to all running shells.