A command-line editor, which supports GNU Emacs or vi(1)-style key bindings. See The command-line editor and Editor commands.
Programmable, interactive word completion and listing. See Completion and listing and the complete and uncomplete builtin commands.
Spelling correction (q.v.) of filenames, commands and variables.
Editor commands (q.v.) which perform other useful functions in the middle of typed commands, including documentation lookup (run-help), quick editor restarting (run-fg-editor) and command resolution (which-command).
An enhanced history mechanism. Events in the history list are time-stamped. See also the history command and its associated shell variables, the previously undocumented `#' event specifier and new modifiers under History substitution, the *-history, history-search-*, i-search-*, vi-search-* and toggle-literal-history editor commands and the histlit shell variable.
Enhanced directory parsing and directory stack handling. See the cd, pushd, popd and dirs commands and their associated shell variables, the description of Directory stack substitution, the dirstack, owd and symlinks shell variables and the normalize-command and normalize-path editor commands.
Negation in glob-patterns. See Filename substitution.
New File inquiry operators (q.v.) and a filetest builtin which uses them.
A variety of Automatic, periodic and timed events (q.v.) including scheduled events, special aliases, automatic logout and terminal locking, command timing and watching for logins and logouts.
Support for the Native Language System (see Native Language System support), OS variant features (see OS variant support and the echo_style shell variable) and system-dependent file locations (see FILES).
Extensive terminal-managment capabilities. See Terminal management.
New builtin commands including builtins, hup, ls-F, newgrp, printenv, which and where (q.v.).
New variables that make useful information easily available to the shell. See the gid, loginsh, oid, shlvl, tcsh, tty, uid and version shell variables and the HOST, REMOTEHOST, VENDOR, OSTYPE and MACHTYPE environment variables.
A new syntax for including useful information in the prompt string (see prompt). and special prompts for loops and spelling correction (see prompt2 and prompt3).
Read-only variables. See Variable substitution.