Readline may refer either the GNU readline library, used for editing a command line; or a function or method in various programming languages which typically reads a line of text from an open file handle.

GNU readline library

The gnu readline library provides applications with an interactive command prompt with features like

• flexible command editing
• configurable key bindings to mimic e.g. emacs or vi
• a history of past commands
• tab-completion

Probably the most prominent application using readline is bash. Both packages are maintained by the same person. Many programming languages provide bindings for this library.

readline function

Examples of readline functions or methods include

• java.io.BufferedReader.readLine in java
• readline in r

(please extend this list if you know more languages using this name)