COMPILING

rc uses GNU autoconf and automake.  The following commands are all you
need to configure, build, test, and install rc.

    $ sh configure
    $ make
    $ make trip
    # make install

This will build rc in the source directory (see below for details on how
to build rc in a different directory).


BUILD AND CONFIGURATION OPTIONS

There are lots of options you can give to configure to modify rc's
behaviour.  You can also select a command line history library to
link against---see the README file for details of where to find these
libraries.  For a summary of all options, run `sh configure --help'.

You can specify Makefile variables by setting the corresponding
environment variables.  For example, you might want to set `CC=cc', to
prevent configure looking for gcc, or set an initial value for `LIBS',
as in the example below.  It is a good idea to specify static linking
(unless you are linking against a dynamic readline library)---if you are
using gcc, you can do this by setting `CFLAGS=-static'.

Here are the configure options you may want to use, in approximately
descending order of usefulness.

  --with-editline

  This option tells rc to use the editline package (see the README file
  for details) to provide EMACS style command line editing and history.
  If the editline library is not installed in a standard place, you can
  tell configure where to find it by setting the environment variable
  LDFLAGS.  For example, the maintainer builds rc by copying libedit.a
  into the rc build directory and then running this configure command.

    LDFLAGS=-L. sh ../rc-1.5b3/configure --with-editline

  --with-vrl

  This option tells rc to use the vrl package (see the README file for
  details) to provide EMACS style command line editing and history.  As
  for `--with-editline', you may need to set the environment variable
  LDFLAGS appropriately.

  --with-readline

  This option tells rc to use the GNU readline package, which is similar
  to editline or vrl, but has many more features.  The readline package
  is over 6 times the size of editline (whether you count lines of code,
  or the library itself).  As for editline, you can set the environment
  variable LDFLAGS if your readline library is not installed in a
  standard place.

    LDFLAGS=-L/usr/gnu/lib sh configure --with-readline

  --with-history

  Use this option if you want to build and install the programs that
  support a crude history mechanism.

You can't use more than one of `--with-editline', `--with-vrl', and
`--with-readline' at the same time.  If you have any of these you
probably don't want to bother with `--with-history'.

  --prefix /path

  By default, `prefix' is /usr/local, which means that `make install'
  installs rc (and possibly the history programs) in /usr/local/bin, and
  man pages in /usr/local/man/man1.  Use this option to change where
  `make install' puts things.

  --disable-builtin-echo

  By default, the `echo' command is builtin to rc for reasons of
  efficiency and portability (of rc scripts).  It is the only builtin
  which is not essential, and purists may wish to omit it.  Note that
  `make trip' will fail if you disable builtin echo and your system's
  `echo' does not understand `-n' to suppress newline.

  --with-addon
  --with-addon=foo.c
  
  On the other hand, non-purists may wish to add extra builtin commands.
  An example is included in the files addon.c and addon.h, which will
  only be built if you specify `--with-addon'.  If your addons are
  in another file, you can specify that instead (but beware that the
  interface file is still addon.h).

  --disable-def-interp
  --enable-def-interp=/bin/foo

  By default, a program that fails with "Exec format error" is handed to
  /bin/sh.  This does the Right Thing for scripts that start with `:' to
  indicate that they are sh scripts.  You can disable this behaviour
  entirely, or specify a different default interpreter.

  --disable-def-path
  --enable-def-path "/usr/local/bin","/usr/bin"

  By default, if rc is started with no PATH, it uses a default path.
  The default path is constructed at configure time, and consists
  of each of the following directories that exist, in order.

      /usr/local/bin /usr/bin /usr/bsd /usr/ucb /bin .

  You can disable this, or specify a different default path.  Note that
  the quote marks (") must be seen by configure; unless you are already
  using rc, you will probably need to quote them to your shell.

  --disable-job

  By default, rc puts backgrounded processes into a new process group,
  as though it were a job control shell (it isn't).  This is usually
  needed to work around bugs in application programs which install
  signal handlers for the keyboard signals without checking whether the
  signal was being ignored.  This option disables the default behaviour,
  making rc behave like a traditional sh.  You are unlikely to want this
  option on any Unix system.

  --disable-protect-env

  By default, rc encodes special characters in environment variables.
  This is necessary on all known Unix systems to prevent sh either
  dying or discarding the variables.  This option disables the default
  behaviour.  You are unlikely to want this option on any Unix system.

After you've built rc, I recommend that you run it through a test script
to gain some confidence that all is working well.  Type `make trip' to
do this.  This will produce some output, and should end with "trip is
complete".  If the trip instead ends with "trip took a wrong turn..."
please contact the maintainer.


LARGE FILE SUPPORT

This release of rc supports large files (i.e. with 64 bit offsets), on
systems where the configure script can figure out how to enable this.
When you run `make trip' (you always run `make trip', right?) the
penultimate line of output (before "trip complete") reports whether
large file support seems to be working or not.

Large file support is a function of file systems, as well as
applications.  For example, NFS and tmpfs file systems often do not
support large files.  The test used by `make trip' is therefore
subject to false negatives.  That is, a report that "large file
support seems NOT to be working" may be erroneous.  To minimise this
possibility, the test is performed both in the current directory
(where you built rc) and /tmp.  (I don't think there's any scenario
where a false positive can be reported.)


BUILDING IN ANOTHER DIRECTORY

If you have a suitable `make', you can build rc in a different directory
from where the sources are held.  This is particularly useful if you
are building rc for multiple architectures.  All you need do is specify
the path to the configure script in the first step.  Suitable `make's
include GNU, HP-UX, and SunOS, but not Irix, nor Ultrix, nor UnixWare.


COMPILATION WARNINGS

If your C compiler is gcc, the option `-Wall' is turned on.  This may
produce a few warnings.

Warnings about "implicit declaration" of system functions may occur if
your system's include files are deficient---they are usually harmless.

Some older versions of gcc warn about "variable `n' might be
clobbered" in walk.c.  As far as I can tell, this is gcc telling you
that it might not be compiling the code correctly!  I don't know how
to eliminate the warning, but it doesn't appear to cause any problems
in practice.

On some systems there are warnings about "passing arg 2 of `getgroups'
from incompatible pointer type" in which.c.  I believe this is due to an
incorrect declaration of `getgroups()' in those systems' header files.

Any other warnings should be reported to the maintainer.


OLD C

rc needs an ISO C (89) compiler, or at least one that has a reasonable
understanding of function prototypes, `<stdarg.h>', `void', and
`volatile'.  If you really need to compile rc with an ancient C
compiler, please contact the maintainer.