Introduction

This is the Gnu Readline library, version 8.1.

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] General Public License as published by the Free Software Foundation, version 3 of the License. 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.

The special make target `everything' will build the static and shared libraries (if the target platform supports them) and the examples.

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.

If configure' is given the --enable-shared' option, it will attempt to build the shared libraries by default 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 4.2 with any version of gcc is identified as freebsd4.2-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_LIBPREF The prefix to use when generating the filename of the shared library. The default is lib'; Cygwin uses cyg'.

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_DLLVERSION The version number for shared libraries that determines API compatibility between readline versions and the underlying system. Used only on Cygwin. Defaults to $SHLIB_MAJOR, but can be overridden at configuration time by defining DLLVERSION in the environment.

SHLIB_DOT The character used to separate the name of the shared library from the suffix and version information. The default is `.'; systems like Cygwin which don't separate version information from the library name should set this to the empty string.

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.

If shared libraries are created, make install' will install them. You may install only the shared libraries by running make install-shared' from the top-level build directory. Running make install' in the shlib subdirectory will also work. If you don't want to install any created shared libraries, run make install-static'.

Documentation

The documentation for the Readline and History libraries appears in the doc' subdirectory. There are three texinfo files and a Unix-style manual page describing the facilities available in the Readline library. The texinfo files include both user and programmer's manuals. HTML versions of the manuals appear in the doc' subdirectory as well.

Usage

Our position on the use of Readline through a shared-library linking mechanism is that there is no legal difference between shared-library linking and static linking--either kind of linking combines various modules into a single larger work. The conditions for using Readline in a larger work are stated in section 3 of the GNU GPL.

Reporting Bugs

Bug reports for Readline should be sent to:

    [email protected]

When reporting a bug, please include the following information:

    * the version number and release status of Readline (e.g., 4.2-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 [email protected].

Since Readline is developed along with bash, the [email protected] mailing list (mirrored to the Usenet newsgroup gnu.bash.bug) often contains Readline bug reports and fixes.

Chet Ramey [email protected]