Provides generic line editing, history, and tokenization functions. See https://www.php.net/manual/en/book.readline.php

C variables starting with rl_* are declared by the readline library (or are macros referring to variables from the libedit library). See http://web.mit.edu/gnu/doc/html/rlman_2.html

This should only be used in the CLI SAPI. Historically, the code lived in sapi/cli, but many distributions build readline as a shared extension. Therefore, that code was split into ext/readline so that this can dynamically be loaded. With other SAPIs, readline is/should be disabled.

readline_cli.c implements most of the interactive shell(php -a).