This release fixes several outstanding bugs in bash-4.4 and introduces several new features. The most significant bug fixes are an overhaul of hownameref variables resolve and a number of potential out-of-bounds memory errors discovered via fuzzing. There are a number of changes to the expansion of $@ and $* in various contexts where word splitting is not performed to conform to a Posix standard interpretation, and additional changes to resolve corner cases for Posix conformance.
The most notable new features are several new shell variables: BASH_ARGV0, EPOCHSECONDS, and EPOCHREALTIME. The ‘history’ builtin can remove ranges of history entries and understands negative arguments as offsets from the end of the history list. There is an option to allow local variables to inherit the value of a variable with the same name at a preceding scope. There is a new shell option that, when enabled, causes the shell to attempt to expand associative array subscripts only once (this is an issue when they are used in arithmetic expressions). The ‘globasciiranges’ shell option is now enabled by default; it can be set to off by default at configuration time.