Readline

GNU Readline is a software library that provides line-editing and history capabilities for interactive programs with a command-line interface, such as Bash. It is currently maintained by Chet Ramey as part of the GNU Project.

It allows users to move the text cursor, search the command history, control a kill ring (a more flexible version of a copy/paste clipboard) and use tab completion on a text terminal. As a cross-platform library, readline allows applications on various systems to exhibit identical line-editing behavior.

Readline supports both Emacs and vi editing modes, which determine how keyboard input is interpreted as editor commands. See Editor war#Differences between vi and Emacs.

Emacs editing mode key bindings are taken from the text editor Emacs.

On some systems, Esc must be used instead of Alt, because the Alt shortcut conflicts with another shortcut. For example, pressing Alt+f in Xfce's terminal emulator window does not move the cursor forward one word, but activates "File" in the menu of the terminal window, unless that is disabled in the emulator's settings.