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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
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
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.
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
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 $SHOBJ_CC. If you are using
gcc, a value of `gcc' will probably work.
SHOBJ_LDFLAGS Flags to pass to SHOBJ_LD to enable shared object creation.
If you are using gcc, `-shared' may be all that is necessary.
These should be the flags needed for generic shared object
SHLIB_XLDFLAGS Additional flags to pass to SHOBJ_LD for shared library
creation. Many systems use the -R option to the link
editor to embed a path within the library for run-time
library searches. A reasonable value for such systems would
be `-R$(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 $(SHLIB_LIBSUFF),
and possibly include version information that allows the
run-time loader to load the version of the shared library
appropriate for a particular program. Systems using shared
libraries similar to SunOS 4.x use major and minor library
version numbers; for those systems a value of
Systems based on System V Release 4 don't use minor version
numbers; use `$(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
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'.
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.
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:
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
* 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
Since Readline is developed along with bash, the mailing
list (mirrored to the Usenet newsgroup gnu.bash.bug) often contains
Readline bug reports and fixes.
Chet Ramey