source: trunk/third/readline/README @ 12992

Introduction
============

This is the Gnu Readline library, version 4.0.

The Readline library provides a set of functions for use by applications
that allow users to edit command lines as they are typed in.  Both
Emacs and vi editing modes are available.  The Readline library includes
additional functions to maintain a list of previously-entered command
lines, to recall and perhaps reedit those lines, and perform csh-like
history expansion on previous commands.

The history facilites are also placed into a separate library, the
History library, as part of the build process.  The History library
may be used without Readline in applications which desire its
capabilities.

The Readline library is free software, distributed under the terms of
the GNU Public License, version 2.  For more information, see the file
COPYING.

To build the library, try typing `./configure', then `make'.  The
configuration process is automated, so no further intervention should
be necessary.  Readline builds with `gcc' by default if it is
available.  If you want to use `cc' instead, type

        CC=cc ./configure

if you are using a Bourne-style shell.  If you are not, the following
may work:

        env CC=cc ./configure

Read the file INSTALL in this directory for more information about how
to customize and control the build process.

The file rlconf.h contains C preprocessor defines that enable and disable
certain Readline features.

Examples
========

There are several example programs that use Readline features in the
examples directory.  The `rl' program is of particular interest.  It
is a command-line interface to Readline, suitable for use in shell
scripts in place of `read'.

Shared Libraries
================

There is skeletal support for building shared versions of the
Readline and History libraries.  The configure script creates
a Makefile in the `shlib' subdirectory, and typing `make shared'
will cause shared versions of the Readline and History libraries
to be built on supported platforms.

Configure calls the script support/shobj-conf to test whether or
not shared library creation is supported and to generate the values
of variables that are substituted into shlib/Makefile.  If you
try to build shared libraries on an unsupported platform, `make'
will display a message asking you to update support/shobj-conf for
your platform.

If you need to update support/shobj-conf, you will need to create
a `stanza' for your operating system and compiler.  The script uses
the value of host_os and ${CC} as determined by configure.  For
instance, FreeBSD 2.2.5 with any version of gcc is identified as
`freebsd2.2.5-gcc*'.

In the stanza for your operating system-compiler pair, you will need to
define several variables.  They are:

SHOBJ_CC        The C compiler used to compile source files into shareable
                object files.  This is normally set to the value of ${CC}
                by configure, and should not need to be changed.

SHOBJ_CFLAGS    Flags to pass to the C compiler ($SHOBJ_CC) to create
                position-independent code.  If you are using gcc, this
                should probably be set to `-fpic'.

SHOBJ_LD        The link editor to be used to create the shared library from
                the object files created by $SHOBJ_CC.  If you are using
                gcc, a value of `gcc' will probably work.

SHOBJ_LDFLAGS   Flags to pass to SHOBJ_LD to enable shared object creation.
                If you are using gcc, `-shared' may be all that is necessary.
                These should be the flags needed for generic shared object
                creation.

SHLIB_XLDFLAGS  Additional flags to pass to SHOBJ_LD for shared library
                creation.  Many systems use the -R option to the link
                editor to embed a path within the library for run-time
                library searches.  A reasonable value for such systems would
                be `-R$(libdir)'.

SHLIB_LIBS      Any additional libraries that shared libraries should be
                linked against when they are created.

SHLIB_LIBSUFF   The suffix to add to `libreadline' and `libhistory' when
                generating the filename of the shared library.  Many systems
                use `so'; HP-UX uses `sl'.

SHLIB_LIBVERSION The string to append to the filename to indicate the version
                of the shared library.  It should begin with $(SHLIB_LIBSUFF),
                and possibly include version information that allows the
                run-time loader to load the version of the shared library
                appropriate for a particular program.  Systems using shared
                libraries similar to SunOS 4.x use major and minor library
                version numbers; for those systems a value of
                `$(SHLIB_LIBSUFF).$(SHLIB_MAJOR)$(SHLIB_MINOR)' is appropriate.
                Systems based on System V Release 4 don't use minor version
                numbers; use `$(SHLIB_LIBSUFF).$(SHLIB_MAJOR)' on those systems.
                Other Unix versions use different schemes.

SHLIB_STATUS    Set this to `supported' when you have defined the other
                necessary variables.  Make uses this to determine whether
                or not shared library creation should be attempted.

You should look at the existing stanzas in support/shobj-conf for ideas.

Once you have updated support/shobj-conf, re-run configure and type
`make shared'.  The shared libraries will be created in the shlib
subdirectory.

Since shared libraries are not created on all platforms, `make install'
will not automatically install the shared libraries.  To install them,
change the current directory to shlib and type `make install'.  Running
`make install-shared' from the top-level build directory will also work.

Documentation
=============

The documentation for the Readline and History libraries appears in the
`doc' subdirectory.  There are two texinfo files and a Unix-style manual
page describing the programming facilities available in the Readline
library.  The texinfo files include both user and programmer's manuals.

Reporting Bugs
==============

Bug reports for Readline should be sent to:

        bug-readline@gnu.org

When reporting a bug, please include the following information:

        * the version number and release status of Readline (e.g., 4.0-release)
        * the machine and OS that it is running on
        * a list of the compilation flags or the contents of `config.h', if
          appropriate
        * a description of the bug
        * a recipe for recreating the bug reliably
        * a fix for the bug if you have one!

If you would like to contact the Readline maintainer directly, send mail
to bash-maintainers@gnu.org.

Since Readline is developed along with bash, the bug-bash@gnu.org mailing
list (mirrored to the Usenet newsgroup gnu.bash.bug) often contains
Readline bug reports and fixes. 

Chet Ramey
chet@po.cwru.edu