The readline() functions implement an
interface to the GNU Readline library. These are
functions that provide editable command lines. An
example being the way Bash allows you to use the arrow
keys to insert characters or scroll through command
history. Because of the interactive nature of this
library, it will be of little use for writing Web
applications, but may be useful when writing scripts
meant using PHP
from the command line.
注: This extension is not available on Windows platforms.
To use the readline functions, you need to install
libreadline. You can find libreadline on the home page
of the GNU Readline project, at
http://cnswww.cns.cwru.edu/~chet/readline/rltop.html.
It's maintained by Chet Ramey, who's also the author of
Bash.
You can also use this functions with the libedit
library, a non-GPL replacement for the readline
library. The libedit library is BSD licensend and
available for download from
http://sourceforge.net/projects/libedit/.