This is release 1.5b2 of rc.

Read COPYRIGHT for copying information.  All files are

   Copyright 1991, 1997 Byron Rakitzis.

COMPILING

rc was written in portable ANSI C.  If you don't have an ANSI compiler
like gcc or something close (e.g., sgi's cc) read further down on
how to convert rc's source to old C.

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

    $ sh configure
    $ make
    $ make trip
    # make install

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.  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.

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

  --with-editline

  This option tells rc to use Simmule Turner's and Rich $alz's editline
  package, which you can get from the following location.  This is
  essentially a lightweight version of GNU readline, providing EMACS
  style command line editing and history.

    ftp://ftp.pipex.net/people/tim/editline.tar.gz

  If the editline library is not installed in a standard place, you
  can tell configure where to find it by setting the environment
  variable LIBS.  For example, the maintainer builds rc by copying
  libedit.a into the rc directory and then running this configure
  command.

    LIBS=-L. sh configure --with-editline

  --with-readline

  This option tells rc to use the GNU readline package, which is similar
  to editline, 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).  You probably need to tell the compiler to link with
  the termcap library if you're using readline.  For example, here is
  the configure command the maintainer uses to build rc with readline.

    LIBS=-ltermcap sh configure --with-readline

  --enable-history

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

You can't use `--with-editline' and `--with-readline' together, of course,
and if you have either of those you probably don't want to bother with
`--enable-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 efficiency reasons.
  It is the only builtin which is not essential, and purists may wish
  to omit it.

  --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/ucb /bin .

  You can disable this, or specify a different default path.  Note
  that the quote marks (") must be seen by configure; you will
  probably need to quote them to your shell.  (Not if it's already
  rc, but then you will need to quote the `='.)

  --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, you may wish to run it through a test script
to see that everything is ok.  Type `make trip' for this.  This will
produce some output, and end with "trip is complete".  If the trip ends
with "trip took a wrong turn..." please contact the maintainer.  (If
you've built in either of the command line history libraries, the trip
will fail near the end with `trip took a wrong turn: dot -i'.)

BUGS

Send bug reports to <tim@uk.uu.net> (<tgoodwin@cygnus.co.uk> after
1997-07-27).  If a core dump is generated, sending a backtrace will
help a great deal.  You can get a backtrace like this.

	; gdb rc core
	(gdb) where
	<<<BACKTRACE INFO>>>
	(gdb)

Also, always report the machine, OS (`uname -a'), and compiler used to
make rc; this information is extremely valuable.

FEEPING CREATURISM

See the end of the man page, under "INCOMPATABILITIES" for (known?)
differences from the "real" rc.  Most of these changes were necessary
to get rc to work in a reasonable fashion on a real (i.e.  commercial,
non-Labs) Unix system; a few were changes motivated by concern about
some inadequacies in the original design.

YACC

The yacc that Sun ships with SunOS 4.1.1 calls malloc() to allocate
space for the state stack, and requires a call to YYACCEPT or YYABORT to
free this memory.  This means that if rc takes an interrupt while parsing
a command (say, if ^C is typed), yacc will leak away this memory.  The
solution is to use a yacc which statically allocates this array, such
as the yacc in the BSD distribution.  Berkeley yacc-generated y.tab.c
and y.tab.h are shipped with rc in case you cannot get hold of Berkeley
yacc.

OLD C

If you need to convert rc's source into K&R C, you need to run the
source through a filter called "unproto", posted in comp.sources.misc.
A sample "cpp" shell script that I used to run unproto under SunOS is
supplied with rc.

CREDITS

This shell was written by me, Byron Rakitzis, but kudos go to Paul Haahr
for letting me know what a shell should do and for contributing certain
bits and pieces to rc (notably the limits code, print.c, most of which.c
and the backquote redirection code), and to Hugh Redelmeier for running
rc through his fussy ANSI compiler and thereby provoking interesting
discussions about portability, and also for providing many valuable
suggestions for improving rc's code in general.  Finally, many thanks
go to David Sanderson, for reworking the man page to format well with
troff, and for providing many suggestions both for rc and its man page.

Thanks to Boyd Roberts for the original history.c, and to Hugh again for
re-working parts of that code.

Of course, without Tom Duff's design of the original rc, I could not
have written this shell (though I probably would have written *a*
shell).  Almost of all of the features, with minor exceptions, have been
implemented as described in the Unix v10 manuals.  Hats off to td for
designing a C-like, minimal but very useful shell.

Tom Duff has kindly given permission for the paper he wrote for UKUUG to
be distributed with this version of rc (called "plan9.ps" in the same
ftp directory as the shell).  Please read this paper bearing in mind that
it describes a program that was written at AT&T and that the version of
rc presented here differs in some respects.

The current maintainer of rc is Tim Goodwin, <tim@uk.uu.net>
(<tgoodwin@cygnus.co.uk> after 1997-07-27).