diff --git a/Makefile.am b/Makefile.am
index 52961492..8d141efd 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -18,7 +18,7 @@ distclean-local:
 
 clean-local:
 	rm -rf $(builddir)/go.mod $(builddir)/go.sum
-	go clean -C $(srcdir) -x -modfile $(abs_builddir)/go.mod -cache
+	go clean -C $(srcdir) -x -modfile $(abs_srcdir)/go.mod -cache
 
 ######################################################################
 if ENABLE_HAWKGO
@@ -35,8 +35,8 @@ hawkgo.check:
 	CC=$(CC) \
 	CGO_CFLAGS="-I$(abs_srcdir)/lib -I$(abs_builddir)/lib $(CFLAGS) $(CGO_CFLAGS_EXTRA) $(CGO_CFLAGS_ADD)" \
 	CGO_LDFLAGS="-L$(abs_builddir)/lib -L$(abs_builddir)/lib/.libs -lhawk -ldl $(LIBM) $(CGO_LDFLAGS_EXTRA) $(CGO_LDFLAGS_ADD)"  \
-	go test -C $(srcdir) -ldflags "-X 'main.BINDIR=$(bindir)' -X 'main.SBINDIR=$(sbindir)' -X 'main.LIBDIR=$(libdir)' -X 'main.SYSCONFDIR=$(sysconfdir)'" -x -modfile $(abs_builddir)/go.mod
-	go clean -C $(srcdir) -x -modfile $(abs_builddir)/go.mod
+	go test -C $(srcdir) -ldflags "-X 'main.BINDIR=$(bindir)' -X 'main.SBINDIR=$(sbindir)' -X 'main.LIBDIR=$(libdir)' -X 'main.SYSCONFDIR=$(sysconfdir)'" -x -modfile $(abs_srcdir)/go.mod
+	go clean -C $(srcdir) -x -modfile $(abs_srcdir)/go.mod
 
 endif
 ######################################################################
diff --git a/Makefile.in b/Makefile.in
index 2ebabb97..a7a32a26 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -877,14 +877,14 @@ distclean-local:
 
 clean-local:
 	rm -rf $(builddir)/go.mod $(builddir)/go.sum
-	go clean -C $(srcdir) -x -modfile $(abs_builddir)/go.mod -cache
+	go clean -C $(srcdir) -x -modfile $(abs_srcdir)/go.mod -cache
 
 @ENABLE_HAWKGO_TRUE@hawkgo.check:
 @ENABLE_HAWKGO_TRUE@	CC=$(CC) \
 @ENABLE_HAWKGO_TRUE@	CGO_CFLAGS="-I$(abs_srcdir)/lib -I$(abs_builddir)/lib $(CFLAGS) $(CGO_CFLAGS_EXTRA) $(CGO_CFLAGS_ADD)" \
 @ENABLE_HAWKGO_TRUE@	CGO_LDFLAGS="-L$(abs_builddir)/lib -L$(abs_builddir)/lib/.libs -lhawk -ldl $(LIBM) $(CGO_LDFLAGS_EXTRA) $(CGO_LDFLAGS_ADD)"  \
-@ENABLE_HAWKGO_TRUE@	go test -C $(srcdir) -ldflags "-X 'main.BINDIR=$(bindir)' -X 'main.SBINDIR=$(sbindir)' -X 'main.LIBDIR=$(libdir)' -X 'main.SYSCONFDIR=$(sysconfdir)'" -x -modfile $(abs_builddir)/go.mod
-@ENABLE_HAWKGO_TRUE@	go clean -C $(srcdir) -x -modfile $(abs_builddir)/go.mod
+@ENABLE_HAWKGO_TRUE@	go test -C $(srcdir) -ldflags "-X 'main.BINDIR=$(bindir)' -X 'main.SBINDIR=$(sbindir)' -X 'main.LIBDIR=$(libdir)' -X 'main.SYSCONFDIR=$(sysconfdir)'" -x -modfile $(abs_srcdir)/go.mod
+@ENABLE_HAWKGO_TRUE@	go clean -C $(srcdir) -x -modfile $(abs_srcdir)/go.mod
 
 ######################################################################
 
diff --git a/bin/Makefile.am b/bin/Makefile.am
index 25bc36cb..f2c84a66 100644
--- a/bin/Makefile.am
+++ b/bin/Makefile.am
@@ -38,8 +38,6 @@ hawk_LDFLAGS = $(LDFLAGS_COMMON)
 ##
 hawk_LDADD = $(LIBADD_COMMON) $(LIBM)
 
-
-
 if ENABLE_HAWKGO
 
 ## the attempt to compose a proper procedure using a regular compiler failed.
@@ -52,9 +50,9 @@ if ENABLE_HAWKGO
 
 bin_PROGRAMS += hawkgo
 hawkgo_SOURCES = \
-	../go.mod \
 	../hawk.go \
 	../hawk-inst.go \
+	getopt.go \
 	hawkgo.go
 ##hawkgo_DEPENDENCIES = 
 
@@ -71,16 +69,16 @@ CGO_LDFLAGS_ADD=""
 endif
 
 hawkgo$(EXEEXT): ../lib/libhawk.la $(hawkgo_OBJECTS)
-	cp -pf $(top_srcdir)/go.mod $(builddir)/go.mod >/dev/null 2>&1 || true
-	chmod u+w $(builddir)/go.mod ## with `make distcheck`, the echo's redirection to the file fails without this permission change
+	##cp -pf $(top_srcdir)/go.mod $(builddir)/go.mod >/dev/null 2>&1 || true
+	##chmod u+w $(builddir)/go.mod ## with `make distcheck`, the echo's redirection to the file fails without this permission change
 	[ -f $(srcdir)/go.sum ] && cp -pf $(srcdir)/go.sum $(builddir)/go.sum >/dev/null 2>&1 || true
 	## ---------------------------------------------------------------
 	CC=$(CC) \
 	CGO_CFLAGS="-I$(abs_top_srcdir)/lib -I$(abs_top_builddir)/lib $(CFLAGS) $(CGO_CFLAGS_EXTRA) $(CGO_CFLAGS_ADD)" \
 	CGO_LDFLAGS="-L$(abs_top_builddir)/lib -L$(abs_top_builddir)/lib/.libs -lhawk -ldl $(LIBM) $(CGO_LDFLAGS_EXTRA) $(CGO_LDFLAGS_ADD)"  \
-	go build -C $(srcdir) -ldflags "-X 'main.BINDIR=$(bindir)' -X 'main.SBINDIR=$(sbindir)' -X 'main.LIBDIR=$(libdir)' -X 'main.SYSCONFDIR=$(sysconfdir)'" -x -o $(abs_builddir)/$@ -modfile $(abs_builddir)/go.mod  $(abs_srcdir)/hawkgo.go
+	go build -C $(srcdir) -ldflags "-X 'main.BINDIR=$(bindir)' -X 'main.SBINDIR=$(sbindir)' -X 'main.LIBDIR=$(libdir)' -X 'main.SYSCONFDIR=$(sysconfdir)'" -x -o $(abs_builddir)/$@ -modfile $(abs_top_srcdir)/go.mod  $(abs_srcdir)/hawkgo.go $(abs_srcdir)/getopt.go
 	## ---------------------------------------------------------------
-	go clean -C $(srcdir) -x -modfile $(abs_builddir)/go.mod
+	go clean -C $(srcdir) -x -modfile $(abs_top_srcdir)/go.mod
 
 ## the go to o recipe is fake to deceive make
 .go.o:
diff --git a/bin/Makefile.in b/bin/Makefile.in
index 91eba7d2..8259f091 100644
--- a/bin/Makefile.in
+++ b/bin/Makefile.in
@@ -125,11 +125,11 @@ am__v_lt_1 =
 hawk_LINK = $(LIBTOOL) $(AM_V_lt) --tag=CC $(AM_LIBTOOLFLAGS) \
 	$(LIBTOOLFLAGS) --mode=link $(CCLD) $(hawk_CFLAGS) $(CFLAGS) \
 	$(hawk_LDFLAGS) $(LDFLAGS) -o $@
-am__hawkgo_SOURCES_DIST = ../go.mod ../hawk.go ../hawk-inst.go \
+am__hawkgo_SOURCES_DIST = ../hawk.go ../hawk-inst.go getopt.go \
 	hawkgo.go
 am__dirstamp = $(am__leading_dot)dirstamp
-@ENABLE_HAWKGO_TRUE@am_hawkgo_OBJECTS = ../go.$(OBJEXT) \
-@ENABLE_HAWKGO_TRUE@	../hawk.$(OBJEXT) ../hawk-inst.$(OBJEXT) \
+@ENABLE_HAWKGO_TRUE@am_hawkgo_OBJECTS = ../hawk.$(OBJEXT) \
+@ENABLE_HAWKGO_TRUE@	../hawk-inst.$(OBJEXT) getopt.$(OBJEXT) \
 @ENABLE_HAWKGO_TRUE@	hawkgo.$(OBJEXT)
 hawkgo_OBJECTS = $(am_hawkgo_OBJECTS)
 hawkgo_LDADD = $(LDADD)
@@ -372,9 +372,9 @@ hawk_CFLAGS = $(CFLAGS_COMMON)
 hawk_LDFLAGS = $(LDFLAGS_COMMON)
 hawk_LDADD = $(LIBADD_COMMON) $(LIBM)
 @ENABLE_HAWKGO_TRUE@hawkgo_SOURCES = \
-@ENABLE_HAWKGO_TRUE@	../go.mod \
 @ENABLE_HAWKGO_TRUE@	../hawk.go \
 @ENABLE_HAWKGO_TRUE@	../hawk-inst.go \
+@ENABLE_HAWKGO_TRUE@	getopt.go \
 @ENABLE_HAWKGO_TRUE@	hawkgo.go
 
 @ENABLE_HAWKGO_TRUE@hawkgo_LINK = 
@@ -469,7 +469,6 @@ hawk$(EXEEXT): $(hawk_OBJECTS) $(hawk_DEPENDENCIES) $(EXTRA_hawk_DEPENDENCIES)
 ../$(DEPDIR)/$(am__dirstamp):
 	@$(MKDIR_P) ../$(DEPDIR)
 	@: >>../$(DEPDIR)/$(am__dirstamp)
-../go.$(OBJEXT): ../$(am__dirstamp) ../$(DEPDIR)/$(am__dirstamp)
 ../hawk.$(OBJEXT): ../$(am__dirstamp) ../$(DEPDIR)/$(am__dirstamp)
 ../hawk-inst.$(OBJEXT): ../$(am__dirstamp) \
 	../$(DEPDIR)/$(am__dirstamp)
@@ -802,14 +801,12 @@ uninstall-am: uninstall-binPROGRAMS
 
 
 @ENABLE_HAWKGO_TRUE@hawkgo$(EXEEXT): ../lib/libhawk.la $(hawkgo_OBJECTS)
-@ENABLE_HAWKGO_TRUE@	cp -pf $(top_srcdir)/go.mod $(builddir)/go.mod >/dev/null 2>&1 || true
-@ENABLE_HAWKGO_TRUE@	chmod u+w $(builddir)/go.mod ## with `make distcheck`, the echo's redirection to the file fails without this permission change
 @ENABLE_HAWKGO_TRUE@	[ -f $(srcdir)/go.sum ] && cp -pf $(srcdir)/go.sum $(builddir)/go.sum >/dev/null 2>&1 || true
 @ENABLE_HAWKGO_TRUE@	CC=$(CC) \
 @ENABLE_HAWKGO_TRUE@	CGO_CFLAGS="-I$(abs_top_srcdir)/lib -I$(abs_top_builddir)/lib $(CFLAGS) $(CGO_CFLAGS_EXTRA) $(CGO_CFLAGS_ADD)" \
 @ENABLE_HAWKGO_TRUE@	CGO_LDFLAGS="-L$(abs_top_builddir)/lib -L$(abs_top_builddir)/lib/.libs -lhawk -ldl $(LIBM) $(CGO_LDFLAGS_EXTRA) $(CGO_LDFLAGS_ADD)"  \
-@ENABLE_HAWKGO_TRUE@	go build -C $(srcdir) -ldflags "-X 'main.BINDIR=$(bindir)' -X 'main.SBINDIR=$(sbindir)' -X 'main.LIBDIR=$(libdir)' -X 'main.SYSCONFDIR=$(sysconfdir)'" -x -o $(abs_builddir)/$@ -modfile $(abs_builddir)/go.mod  $(abs_srcdir)/hawkgo.go
-@ENABLE_HAWKGO_TRUE@	go clean -C $(srcdir) -x -modfile $(abs_builddir)/go.mod
+@ENABLE_HAWKGO_TRUE@	go build -C $(srcdir) -ldflags "-X 'main.BINDIR=$(bindir)' -X 'main.SBINDIR=$(sbindir)' -X 'main.LIBDIR=$(libdir)' -X 'main.SYSCONFDIR=$(sysconfdir)'" -x -o $(abs_builddir)/$@ -modfile $(abs_top_srcdir)/go.mod  $(abs_srcdir)/hawkgo.go $(abs_srcdir)/getopt.go
+@ENABLE_HAWKGO_TRUE@	go clean -C $(srcdir) -x -modfile $(abs_top_srcdir)/go.mod
 
 @ENABLE_HAWKGO_TRUE@.go.o:
 @ENABLE_HAWKGO_TRUE@	echo $< > $@
diff --git a/bin/getopt.go b/bin/getopt.go
new file mode 100644
index 00000000..49dc775b
--- /dev/null
+++ b/bin/getopt.go
@@ -0,0 +1,424 @@
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package getopt parses command lines using getopt(3) syntax.
+// It is a replacement for flag.Parse but still expects flags themselves
+// to be defined in package flag.
+//
+// Flags defined with one-letter names are available as short flags
+// (invoked using one dash, as in -x) and all flags are available as
+// long flags (invoked using two dashes, as in --x or --xylophone).
+//
+// To use, define flags as usual with package flag. Then introduce
+// any aliases by calling getopt.Alias:
+//
+//	getopt.Alias("n", "dry-run")
+//	getopt.Alias("v", "verbose")
+//
+// Or call getopt.Aliases to define a list of aliases:
+//
+//	getopt.Aliases(
+//		"n", "dry-run",
+//		"v", "verbose",
+//	)
+//
+// One name in each pair must already be defined in package flag
+// (so either "n" or "dry-run", and also either "v" or "verbose").
+//
+// Then parse the command-line:
+//
+//	getopt.Parse()
+//
+// If it encounters an error, Parse calls flag.Usage and then exits the program.
+//
+// When writing a custom flag.Usage function, call getopt.PrintDefaults
+// instead of flag.PrintDefaults to get a usage message that includes the
+// names of aliases in flag descriptions.
+//
+// At initialization time, this package installs a new flag.Usage that is the
+// same as the default flag.Usage except that it calls getopt.PrintDefaults
+// instead of flag.PrintDefaults.
+//
+// This package also defines a FlagSet wrapping the standard flag.FlagSet.
+//
+// Caveat
+//
+// In general Go flag parsing is preferred for new programs, because
+// it is not as pedantic about the number of dashes used to invoke
+// a flag (you can write -verbose or --verbose and the program
+// does not care). This package is meant to be used in situations
+// where, for legacy reasons, it is important to use exactly getopt(3)
+// syntax, such as when rewriting in Go an existing tool that already
+// uses getopt(3).
+package main // import "rsc.io/getopt"
+
+import (
+	"flag"
+	"fmt"
+	"io"
+	"os"
+	"reflect"
+	"strings"
+	"unicode/utf8"
+)
+
+func init() {
+	flag.Usage = func() {
+		fmt.Fprintf(os.Stderr, "Usage of %s:\n", os.Args[0])
+		PrintDefaults() // ours not package flag's
+	}
+
+	CommandLine.FlagSet = flag.CommandLine
+	CommandLine.name = os.Args[0]
+	CommandLine.errorHandling = flag.ExitOnError
+	CommandLine.outw = os.Stderr
+	CommandLine.Usage = func() { flag.Usage() }
+}
+
+var CommandLine FlagSet
+
+// A FlagSet is a set of defined flags.
+// It wraps and provides the same interface as flag.FlagSet
+// but parses command line arguments using getopt syntax.
+//
+// Note that "go doc" shows only the methods customized
+// by package getopt; FlagSet also provides all the methods
+// of the embedded flag.FlagSet, like Bool, Int, NArg, and so on.
+type FlagSet struct {
+	*flag.FlagSet
+
+	alias         map[string]string
+	unalias       map[string]string
+	name          string
+	errorHandling flag.ErrorHandling
+	outw          io.Writer
+}
+
+func (f *FlagSet) out() io.Writer {
+	if f.outw == nil {
+		return os.Stderr
+	}
+	return f.outw
+}
+
+// SetOutput sets the destination for usage and error messages.
+// If output is nil, os.Stderr is used.
+func (f *FlagSet) SetOutput(output io.Writer) {
+	f.FlagSet.SetOutput(output)
+	f.outw = output
+}
+
+// NewFlagSet returns a new, empty flag set with the specified name and error
+// handling property.
+func NewFlagSet(name string, errorHandling flag.ErrorHandling) *FlagSet {
+	f := new(FlagSet)
+	f.Init(name, errorHandling)
+	return f
+}
+
+// Init sets the name and error handling proprety for a flag set.
+func (f *FlagSet) Init(name string, errorHandling flag.ErrorHandling) {
+	if f.FlagSet == nil {
+		f.FlagSet = new(flag.FlagSet)
+	}
+	f.FlagSet.Init(name, errorHandling)
+	f.name = name
+	f.errorHandling = errorHandling
+	f.FlagSet.Usage = f.defaultUsage
+}
+
+func (f *FlagSet) init() {
+	if f.alias == nil {
+		f.alias = make(map[string]string)
+		f.unalias = make(map[string]string)
+	}
+}
+
+// Lookup returns the Flag structure of the named flag,
+// returning nil if none exists.
+// If name is a defined alias for a defined flag,
+// Lookup returns the original flag; in this case
+// the Name field in the result will differ from the
+// name passed to Lookup.
+func (f *FlagSet) Lookup(name string) *flag.Flag {
+	if x, ok := f.alias[name]; ok {
+		name = x
+	}
+	return f.FlagSet.Lookup(name)
+}
+
+// Alias introduces an alias for an existing flag name.
+// The short name must be a single letter, and the long name must be multiple letters.
+// Exactly one name must be defined as a flag already: the undefined name is introduced
+// as an alias for the defined name.
+// Alias panics if both names are already defined or if both are undefined.
+//
+// For example, if a flag named "v" is already defined using package flag,
+// then it is available as -v (or --v). Calling Alias("v", "verbose") makes the same
+// flag also available as --verbose.
+func Alias(short, long string) {
+	CommandLine.Alias(short, long)
+}
+
+// Alias introduces an alias for an existing flag name.
+// The short name must be a single letter, and the long name must be multiple letters.
+// Exactly one name must be defined as a flag already: the undefined name is introduced
+// as an alias for the defined name.
+// Alias panics if both names are already defined or if both are undefined.
+//
+// For example, if a flag named "v" is already defined using package flag,
+// then it is available as -v (or --v). Calling Alias("v", "verbose") makes the same
+// flag also available as --verbose.
+func (f *FlagSet) Alias(short, long string) {
+	f.init()
+	if short == "" || long == "" {
+		panic("Alias: invalid empty flag name")
+	}
+	if utf8.RuneCountInString(short) != 1 {
+		panic("Alias: invalid short flag name -" + short)
+	}
+	if utf8.RuneCountInString(long) == 1 {
+		panic("Alias: invalid long flag name --" + long)
+	}
+
+	f1 := f.Lookup(short)
+	f2 := f.Lookup(long)
+	if f1 == nil && f2 == nil {
+		panic("Alias: neither -" + short + " nor -" + long + " is a defined flag")
+	}
+	if f1 != nil && f2 != nil {
+		panic("Alias: both -" + short + " and -" + long + " are defined flags")
+	}
+
+	if f1 != nil {
+		f.alias[long] = short
+		f.unalias[short] = long
+	} else {
+		f.alias[short] = long
+		f.unalias[long] = short
+	}
+}
+
+// Aliases introduces zero or more aliases. The argument list must consist of an
+// even number of strings making up a sequence of short, long pairs to be passed
+// to Alias.
+func Aliases(list ...string) {
+	CommandLine.Aliases(list...)
+}
+
+// Aliases introduces zero or more aliases. The argument list must consist of an
+// even number of strings making up a sequence of short, long pairs to be passed
+// to Alias.
+func (f *FlagSet) Aliases(list ...string) {
+	if len(list)%2 != 0 {
+		panic("getopt: Aliases not invoked with pairs")
+	}
+	for i := 0; i < len(list); i += 2 {
+		f.Alias(list[i], list[i+1])
+	}
+}
+
+type boolFlag interface {
+	IsBoolFlag() bool
+}
+
+func (f *FlagSet) failf(format string, args ...interface{}) error {
+	err := fmt.Errorf(format, args...)
+	fmt.Fprintln(f.out(), err)
+	f.Usage()
+	return err
+}
+
+// defaultUsage is the default function to print a usage message.
+func (f *FlagSet) defaultUsage() {
+	if f.name == "" {
+		fmt.Fprintf(f.out(), "Usage:\n")
+	} else {
+		fmt.Fprintf(f.out(), "Usage of %s:\n", f.name)
+	}
+	f.PrintDefaults()
+}
+
+// Parse parses the command-line flags from os.Args[1:].
+func Parse() {
+	CommandLine.Parse(os.Args[1:])
+}
+
+// Parse parses flag definitions from the argument list,
+// which should not include the command name.
+// Parse must be called after all flags and aliases in the FlagSet are defined
+// and before flags are accessed by the program.
+// The return value will be flag.ErrHelp if -h or --help were used but not defined.
+func (f *FlagSet) Parse(args []string) error {
+	for len(args) > 0 {
+		arg := args[0]
+		if len(arg) < 2 || arg[0] != '-' {
+			break
+		}
+		args = args[1:]
+		if arg[:2] == "--" {
+			// Process single long option.
+			if arg == "--" {
+				break
+			}
+			name := arg[2:]
+			value := ""
+			haveValue := false
+			if i := strings.Index(name, "="); i >= 0 {
+				name, value = name[:i], name[i+1:]
+				haveValue = true
+			}
+			fg := f.Lookup(name)
+			if fg == nil {
+				if name == "h" || name == "help" {
+					// TODO ErrHelp
+				}
+				return f.failf("flag provided but not defined: --%s", name)
+			}
+			if b, ok := fg.Value.(boolFlag); ok && b.IsBoolFlag() {
+				if haveValue {
+					if err := fg.Value.Set(value); err != nil {
+						return f.failf("invalid boolean value %q for --%s: %v", value, name, err)
+					}
+				} else {
+					if err := fg.Value.Set("true"); err != nil {
+						return f.failf("invalid boolean flag %s: %v", name, err)
+					}
+				}
+				continue
+			}
+			if !haveValue {
+				if len(args) == 0 {
+					return f.failf("missing argument for --%s", name)
+				}
+				value, args = args[0], args[1:]
+			}
+			if err := fg.Value.Set(value); err != nil {
+				return f.failf("invalid value %q for flag --%s: %v", value, name, err)
+			}
+			continue
+		}
+
+		// Process one or more short options.
+		for arg = arg[1:]; arg != ""; {
+			r, size := utf8.DecodeRuneInString(arg)
+			if r == utf8.RuneError && size == 1 {
+				return f.failf("invalid UTF8 in command-line flags")
+			}
+			name := arg[:size]
+			arg = arg[size:]
+			fg := f.Lookup(name)
+			if fg == nil {
+				if name == "h" {
+					// TODO ErrHelp
+				}
+				return f.failf("flag provided but not defined: -%s", name)
+			}
+			if b, ok := fg.Value.(boolFlag); ok && b.IsBoolFlag() {
+				if err := fg.Value.Set("true"); err != nil {
+					return f.failf("invalid boolean flag %s: %v", name, err)
+				}
+				continue
+			}
+			if arg == "" {
+				if len(args) == 0 {
+					return f.failf("missing argument for -%s", name)
+				}
+				arg, args = args[0], args[1:]
+			}
+			if err := fg.Value.Set(arg); err != nil {
+				return f.failf("invalid value %q for flag -%s: %v", arg, name, err)
+			}
+			break // consumed arg
+		}
+	}
+
+	// Arrange for flag.NArg, flag.Args, etc to work properly.
+	f.FlagSet.Parse(append([]string{"--"}, args...))
+	return nil
+}
+
+// PrintDefaults is like flag.PrintDefaults but includes information
+// about short/long alias pairs and prints the correct syntax for
+// long flags.
+func PrintDefaults() {
+	CommandLine.PrintDefaults()
+}
+
+// PrintDefaults is like flag.PrintDefaults but includes information
+// about short/long alias pairs and prints the correct syntax for
+// long flags.
+func (f *FlagSet) PrintDefaults() {
+	f.FlagSet.VisitAll(func(fg *flag.Flag) {
+		name := fg.Name
+		short, long := "", ""
+		other := f.unalias[name]
+		if utf8.RuneCountInString(name) > 1 {
+			long, short = name, other
+		} else {
+			short, long = name, other
+		}
+		var s string
+		if short != "" {
+			s = fmt.Sprintf("  -%s", short) // Two spaces before -; see next two comments.
+			if long != "" {
+				s += ", --" + long
+			}
+		} else {
+			s = fmt.Sprintf("  --%s", long) // Two spaces before -; see next two comments.
+		}
+		name, usage := flag.UnquoteUsage(fg)
+		if len(name) > 0 {
+			s += " " + name
+		}
+
+		// Boolean flags of one ASCII letter are so common we
+		// treat them specially, putting their usage on the same line.
+		if len(s) <= 4 { // space, space, '-', 'x'.
+			s += "\t"
+		} else {
+			// Four spaces before the tab triggers good alignment
+			// for both 4- and 8-space tab stops.
+			s += "\n    \t"
+		}
+		s += usage
+		if !isZeroValue(fg, fg.DefValue) {
+			if strings.HasSuffix(reflect.TypeOf(fg.Value).String(), "stringValue") {
+				// put quotes on the value
+				s += fmt.Sprintf(" (default %q)", fg.DefValue)
+			} else {
+				s += fmt.Sprintf(" (default %v)", fg.DefValue)
+			}
+		}
+		fmt.Fprint(f.out(), s, "\n")
+	})
+}
+
+// isZeroValue guesses whether the string represents the zero
+// value for a flag. It is not accurate but in practice works OK.
+func isZeroValue(f *flag.Flag, value string) bool {
+	// Build a zero value of the flag's Value type, and see if the
+	// result of calling its String method equals the value passed in.
+	// This works unless the Value type is itself an interface type.
+	typ := reflect.TypeOf(f.Value)
+	var z reflect.Value
+	if typ.Kind() == reflect.Ptr {
+		z = reflect.New(typ.Elem())
+	} else {
+		z = reflect.Zero(typ)
+	}
+	if value == z.Interface().(flag.Value).String() {
+		return true
+	}
+
+	switch value {
+	case "false":
+		return true
+	case "":
+		return true
+	case "0":
+		return true
+	}
+	return false
+}
diff --git a/bin/hawkgo.go b/bin/hawkgo.go
index d68332a7..d9488f18 100644
--- a/bin/hawkgo.go
+++ b/bin/hawkgo.go
@@ -5,31 +5,34 @@ import "flag"
 import "fmt"
 import "io"
 import "os"
+import "path/filepath"
 import "runtime"
 import "runtime/debug"
-//import "sync"
-import "time"
+//import "time"
 
 type Config struct {
 	assign string
 	call string
 	fs string
-	srcstr string
-	srcfile string
+	show_extra_info bool
 
-	files []string
+	srcstr string
+	srcfiles []string
+	datfiles []string
 }
 
 func exit_with_error(msg string, err error) {
-	fmt.Printf("ERROR: %s - %s\n", msg, err.Error())
+	fmt.Fprintf(os.Stderr, "ERROR: %s - %s\n", msg, err.Error())
 	os.Exit(1)
 }
 
 func parse_args_to_config(cfg *Config) bool {
-	var flgs *flag.FlagSet
+	//var flgs *flag.FlagSet
+	var flgs *FlagSet
 	var err error
 
-	flgs = flag.NewFlagSet("", flag.ContinueOnError)
+	//flgs = flag.NewFlagSet("", flag.ContinueOnError)
+	flgs = NewFlagSet("", flag.ContinueOnError)
 	flgs.Func("assign", "set a global variable with a value", func(v string) error {
 		cfg.assign = v
 		return nil
@@ -42,16 +45,33 @@ func parse_args_to_config(cfg *Config) bool {
 		cfg.fs = v
 		return nil
 	})
+	flgs.Func("file", "set the source file", func(v string) error {
+		cfg.srcfiles = append(cfg.srcfiles, v)
+		return nil
+	})
+	flgs.BoolVar(&cfg.show_extra_info, "show-extra-info", false, "show extra information")
+
+	flgs.Alias("c", "call")
+	flgs.Alias("D", "show-extra-info")
+	flgs.Alias("F", "field-separator")
+	flgs.Alias("f", "file")
+	flgs.Alias("v", "assign")
 
 	flgs.SetOutput(io.Discard) // prevent usage output
+	//err = flgs.Parse(os.Args[1:])
 	err = flgs.Parse(os.Args[1:])
 	if err != nil {
 		fmt.Fprintf(os.Stderr, "ERROR: %s\n", err.Error())
 		goto wrong_usage
 	}
 
-	if flgs.NArg() == 0 { goto wrong_usage}
-	cfg.files = flgs.Args()
+	//if flgs.NArg() == 0 { goto wrong_usage}
+	cfg.datfiles = flgs.Args()
+	if len(cfg.srcfiles) <= 0 {
+		if len(cfg.datfiles) == 0 { goto wrong_usage }
+		cfg.srcstr = cfg.datfiles[0]
+		cfg.datfiles = cfg.datfiles[1:]
+	}
 
 	return true
 
@@ -88,34 +108,46 @@ func main() {
 	if parse_args_to_config(&cfg) == false { os.Exit(99) }
 fmt.Printf("config [%+v]\n", cfg)
 
-	h, err = make_hawk(`function main(s) {
-print enbase64(s, "hello", 1.289);
-print debase64(s);
-return x
-}`)
+	h, err = hawk.New()
 	if err != nil {
-		fmt.Printf("ERROR: failed to make hawk - %s\n", err.Error())
+		fmt.Fprintf(os.Stderr, "ERROR: failed to make hawk - %s\n", err.Error())
 		return
 	}
 
-	rtx, err = h.NewRtx("test3")
+	if (len(cfg.srcfiles) > 0) {
+		err = h.ParseFiles(cfg.srcfiles)
+	} else {
+		err = h.ParseText(cfg.srcstr)
+	}
 	if err != nil {
-		fmt.Printf("ERROR: failed to make rtx - %s\n", err.Error())
+		fmt.Fprintf(os.Stderr, "ERROR: failed to make hawk - %s\n", err.Error())
+		h.Close()
+		return
+	}
+
+	rtx, err = h.NewRtx(filepath.Base(os.Args[0]), cfg.datfiles)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "ERROR: failed to make rtx - %s\n", err.Error())
 	} else  {
 		var v *hawk.Val
-		v, err = rtx.Call("main", hawk.Must(rtx.NewValFromStr("this is a test3 string")))
-		if err != nil {
-			fmt.Printf("ERROR: failed to make rtx - %s\n", err.Error())
+		if cfg.call != "" {
+			v, err = rtx.Call(cfg.call/*, cfg.datfiles*/) // TODO: pass arguments.
 		} else {
-			fmt.Printf("V=>[%v]\n", v.String())
+			//v, err = rtx.Loop()
+			v, err = rtx.Exec(cfg.datfiles)
+		}
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "ERROR: failed to run rtx - %s\n", err.Error())
+		} else if cfg.show_extra_info {
+			fmt.Printf("[RETURN] - [%v]\n", v.String())
+			// TODO: print global variables and values
 		}
 	}
 
 	h.Close()
-	fmt.Printf ("END OF TEST3\n")
 
 	runtime.GC()
 	runtime.Gosched()
-	time.Sleep(1000 * time.Millisecond) // give finalizer time to print
+//	time.Sleep(1000 * time.Millisecond) // give finalizer time to print
 }
 
diff --git a/hawk.go b/hawk.go
index 0aeb5005..7775435e 100644
--- a/hawk.go
+++ b/hawk.go
@@ -18,7 +18,6 @@ static void init_parsestd_for_text_in(hawk_parsestd_t* in, hawk_bch_t* ptr, hawk
 	in[0].type = HAWK_PARSESTD_BCS;
 	in[0].u.bcs.ptr = ptr;
 	in[0].u.bcs.len = len;
-	in[1].type = HAWK_PARSESTD_NULL;
 }
 
 static void init_parsestd_for_file_in(hawk_parsestd_t* in, hawk_bch_t* path)
@@ -26,7 +25,6 @@ static void init_parsestd_for_file_in(hawk_parsestd_t* in, hawk_bch_t* path)
 	in[0].type = HAWK_PARSESTD_FILEB;
 	in[0].u.fileb.path = path;
 	in[0].u.fileb.cmgr = HAWK_NULL;
-	in[1].type = HAWK_PARSESTD_NULL;
 }
 
 static hawk_ooch_t* valtostr_out_cpldup(hawk_rtx_valtostr_out_t* out, hawk_oow_t* len)
@@ -309,7 +307,10 @@ func (hawk *Hawk) SetLogMask(log_mask BitMask) {
 
 func (hawk *Hawk) AddGlobal(name string) error {
 	var x C.int
-	x = C.hawk_addgblwithbcstr(hawk.c, C.CString(name))
+	var cname *C.hawk_bch_t
+	cname = C.CString(name)
+	x = C.hawk_addgblwithbcstr(hawk.c, cname)
+	C.free(unsafe.Pointer(cname))
 	if x <= -1 { return hawk.make_errinfo() }
 	return nil
 }
@@ -346,29 +347,65 @@ func hawk_go_fnc_handler(rtx_xtn *C.rtx_xtn_t, name *C.hawk_bch_t, namelen C.haw
 
 func (hawk *Hawk) AddFunc(name string, min_args uint, max_args uint, spec string, fn Fnc) error {
 	var fnc *C.hawk_fnc_t
+	var cname *C.hawk_bch_t
+	var cspec *C.hawk_bch_t
 
-	fnc = C.add_fnc_with_bcstr(hawk.c, C.CString(name), C.hawk_oow_t(min_args), C.hawk_oow_t(max_args), C.CString(spec));
+	cname = C.CString(name)
+	cspec = C.CString(spec)
+	fnc = C.add_fnc_with_bcstr(hawk.c, cname, C.hawk_oow_t(min_args), C.hawk_oow_t(max_args), cspec);
+	C.free(unsafe.Pointer(cspec))
+	C.free(unsafe.Pointer(cname))
 	if fnc == nil { return hawk.make_errinfo() }
 
 	hawk.fnctab[name] = fn;
 	return nil
 }
 
-func (hawk *Hawk) ParseFile(text string) error {
+func (hawk *Hawk) ParseFile(file string) error {
 	var x C.int
 	var in [2]C.hawk_parsestd_t
-	C.init_parsestd_for_file_in(&in[0], C.CString(text))
+	var cfile *C.hawk_bch_t
+
+	cfile = C.CString(file)
+	C.init_parsestd_for_file_in(&in[0], cfile)
 	x = C.hawk_parsestd(hawk.c, &in[0], nil)
+	C.free(unsafe.Pointer(cfile))
 	if x <= -1 { return hawk.make_errinfo() }
 	return nil
 }
 
-func (hawk *Hawk) ParseText(text string) error {
+func (hawk *Hawk) ParseFiles(files []string) error {
+	var x C.int
+	var in []C.hawk_parsestd_t
+	var idx int
+	var count int
+	var cfiles []*C.hawk_bch_t
+
+	count = len(files)
+	in = make([]C.hawk_parsestd_t, count + 1)
+	for idx = 0; idx < count; idx++ {
+		cfiles[idx] = C.CString(files[idx])
+		C.init_parsestd_for_file_in(&in[idx], cfiles[idx])
+	}
+	in[idx]._type = C.HAWK_PARSESTD_NULL
+	x = C.hawk_parsestd(hawk.c, &in[0], nil)
+	for idx = 0; idx < count; idx++ {
+		C.free(unsafe.Pointer(cfiles[idx]))
+	}
+	if x <= -1 { return hawk.make_errinfo() }
+	return nil
+}
+
+func (hawk *Hawk) ParseText(file string) error {
 	var x C.int
 	var in [2]C.hawk_parsestd_t
+	var cfile *C.hawk_bch_t
 
-	C.init_parsestd_for_text_in(&in[0], C.CString(text), C.hawk_oow_t(len(text)))
+	cfile = C.CString(file)
+	C.init_parsestd_for_text_in(&in[0], cfile, C.hawk_oow_t(len(file)))
+	in[1]._type = C.HAWK_PARSESTD_NULL
 	x = C.hawk_parsestd(hawk.c, &in[0], nil)
+	C.free(unsafe.Pointer(cfile))
 	if x <= -1 { return hawk.make_errinfo() }
 	return nil
 }
@@ -440,12 +477,32 @@ func deregister_rtx_instance(rtx *Rtx) {
 	}
 }
 
-func (hawk *Hawk) NewRtx(id string) (*Rtx, error) {
+func (hawk *Hawk) NewRtx(id string, in []string) (*Rtx, error) {
 	var rtx *C.hawk_rtx_t
 	var g *Rtx
 	var xtn *C.rtx_xtn_t
+	var cid *C.hawk_bch_t
+	var cin []*C.hawk_bch_t
+	var idx int
+	var in_count int
+
+	in_count = len(in)
+	cin = make([]*C.hawk_bch_t, in_count + 1)
+	for idx = 0; idx < in_count; idx++ {
+		cin[idx] = C.CString(in[idx])
+	}
+	cin[idx] = (*C.hawk_bch_t)(nil)
+	cid = C.CString(id)
+	if in_count > 0 {
+		rtx = C.hawk_rtx_openstdwithbcstr(hawk.c, C.hawk_oow_t(unsafe.Sizeof(*xtn)), cid, &cin[0], nil, nil)
+	} else {
+		rtx = C.hawk_rtx_openstdwithbcstr(hawk.c, C.hawk_oow_t(unsafe.Sizeof(*xtn)), cid, nil, nil, nil)
+	}
+	for idx = 0; idx < in_count; idx++ {
+		C.free(unsafe.Pointer(cin[idx]))
+	}
+	C.free(unsafe.Pointer(cid))
 
-	rtx = C.hawk_rtx_openstdwithbcstr(hawk.c, C.hawk_oow_t(unsafe.Sizeof(*xtn)), C.CString(id), nil, nil, nil)
 	if rtx == nil { return nil, hawk.make_errinfo() }
 
 	g = &Rtx{c: rtx}
@@ -490,6 +547,38 @@ func (rtx *Rtx) make_errinfo() *Err {
 	return &err
 }
 
+func (rtx *Rtx) Exec(args []string) (*Val, error) {
+	var val *C.hawk_val_t
+	var cargs []*C.hawk_bch_t
+	var idx int
+	var count int
+
+	count = len(args)
+	cargs = make([]*C.hawk_bch_t, count)
+	for idx = 0; idx < count; idx++ {
+		cargs[idx] = C.CString(args[idx])
+	}
+
+	if count > 0 {
+		val = C.hawk_rtx_execwithbcstrarr(rtx.c, &cargs[0], C.hawk_oow_t(count))
+	} else {
+		val = C.hawk_rtx_execwithbcstrarr(rtx.c, (**C.hawk_bch_t)(nil), C.hawk_oow_t(count))
+	}
+
+	for idx = 0; idx < count; idx++ {
+		C.free(unsafe.Pointer(cargs[idx]))
+	}
+	if val == nil { return nil, rtx.make_errinfo() }
+	return &Val{rtx: rtx, c: val}, nil
+}
+
+func (rtx *Rtx) Loop() (*Val, error) {
+	var val *C.hawk_val_t
+	val = C.hawk_rtx_loop(rtx.c)
+	if val == nil { return nil, rtx.make_errinfo() }
+	return &Val{rtx: rtx, c: val}, nil
+}
+
 func (rtx *Rtx) Call(name string, args ...*Val) (*Val, error) {
 	var fun *C.hawk_fun_t
 	var val *C.hawk_val_t
@@ -675,7 +764,12 @@ func (rtx *Rtx) NewValFromFlt(v float64) (*Val, error) {
 
 func (rtx *Rtx) NewValFromStr(v string) (*Val, error) {
 	return rtx.make_val(func() *C.hawk_val_t {
-		return C.hawk_rtx_makestrvalwithbchars(rtx.c, C.CString(v), C.hawk_oow_t(len(v)))
+		var vv *C.hawk_val_t
+		var cv *C.hawk_bch_t
+		cv = C.CString(v)
+		vv = C.hawk_rtx_makestrvalwithbchars(rtx.c, cv, C.hawk_oow_t(len(v)))
+		C.free(unsafe.Pointer(cv))
+		return vv
 	})
 }
 
diff --git a/hawk_test.go b/hawk_test.go
index 73e76752..5e793bd9 100644
--- a/hawk_test.go
+++ b/hawk_test.go
@@ -79,7 +79,7 @@ func run_hawk(h *hawk.Hawk, id int, t *testing.T, wg *sync.WaitGroup) {
 
 	defer wg.Done()
 
-	rtx, err = h.NewRtx(fmt.Sprintf("%d", id))
+	rtx, err = h.NewRtx(fmt.Sprintf("%d", id), nil)
 	if err != nil {
 		t.Errorf("failed to create rtx id[%d] - %s", id, err.Error())
 		return
@@ -181,7 +181,7 @@ return x;
 		return
 	}
 
-	rtx, err = h.NewRtx("test2")
+	rtx, err = h.NewRtx("test2", nil)
 	if err != nil {
 		t.Errorf("failed to create rtx - %s", err.Error())
 	} else  {
@@ -310,7 +310,7 @@ return x
 		return
 	}
 
-	rtx, err = h.NewRtx("test3")
+	rtx, err = h.NewRtx("test3", nil)
 	if err != nil {
 		t.Errorf("failed to create rtx - %s", err.Error())
 	} else  {