diff --git a/mio/lib/Makefile.am b/mio/lib/Makefile.am
index d83cee3..1b154b5 100644
--- a/mio/lib/Makefile.am
+++ b/mio/lib/Makefile.am
@@ -37,6 +37,7 @@ include_HEADERS = \
 	mio-http.h \
 	mio-json.h \
 	mio-nwif.h \
+	mio-opt.h \
 	mio-pac1.h \
 	mio-path.h \
 	mio-pipe.h \
@@ -72,6 +73,8 @@ libmio_la_SOURCES = \
 	mio-prv.h \
 	mio.c \
 	nwif.c \
+	opt.c \
+	opt-imp.h \
 	path.c \
 	pipe.c \
 	pro.c \
diff --git a/mio/lib/Makefile.in b/mio/lib/Makefile.in
index 5d11083..9ec8927 100644
--- a/mio/lib/Makefile.in
+++ b/mio/lib/Makefile.in
@@ -150,10 +150,10 @@ libmio_la_DEPENDENCIES = $(am__DEPENDENCIES_2) $(am__DEPENDENCIES_1) \
 am__libmio_la_SOURCES_DIST = chr.c dns.c dns-cli.c ecs.c ecs-imp.h \
 	err.c fmt.c fmt-imp.h htb.c htrd.c htre.c http.c http-cgi.c \
 	http-fil.c http-prv.h http-svr.c http-thr.c http-txt.c json.c \
-	mio-prv.h mio.c nwif.c path.c pipe.c pro.c sck.c skad.c sys.c \
-	sys-ass.c sys-err.c sys-log.c sys-mux.c sys-prv.h sys-tim.c \
-	thr.c uch-case.h uch-prop.h tmr.c utf8.c utl.c utl-siph.c \
-	mar.c mar-cli.c
+	mio-prv.h mio.c nwif.c opt.c opt-imp.h path.c pipe.c pro.c \
+	sck.c skad.c sys.c sys-ass.c sys-err.c sys-log.c sys-mux.c \
+	sys-prv.h sys-tim.c thr.c uch-case.h uch-prop.h tmr.c utf8.c \
+	utl.c utl-siph.c mar.c mar-cli.c
 @ENABLE_MARIADB_TRUE@am__objects_1 = libmio_la-mar.lo \
 @ENABLE_MARIADB_TRUE@	libmio_la-mar-cli.lo
 am_libmio_la_OBJECTS = libmio_la-chr.lo libmio_la-dns.lo \
@@ -162,13 +162,13 @@ am_libmio_la_OBJECTS = libmio_la-chr.lo libmio_la-dns.lo \
 	libmio_la-htre.lo libmio_la-http.lo libmio_la-http-cgi.lo \
 	libmio_la-http-fil.lo libmio_la-http-svr.lo \
 	libmio_la-http-thr.lo libmio_la-http-txt.lo libmio_la-json.lo \
-	libmio_la-mio.lo libmio_la-nwif.lo libmio_la-path.lo \
-	libmio_la-pipe.lo libmio_la-pro.lo libmio_la-sck.lo \
-	libmio_la-skad.lo libmio_la-sys.lo libmio_la-sys-ass.lo \
-	libmio_la-sys-err.lo libmio_la-sys-log.lo libmio_la-sys-mux.lo \
-	libmio_la-sys-tim.lo libmio_la-thr.lo libmio_la-tmr.lo \
-	libmio_la-utf8.lo libmio_la-utl.lo libmio_la-utl-siph.lo \
-	$(am__objects_1)
+	libmio_la-mio.lo libmio_la-nwif.lo libmio_la-opt.lo \
+	libmio_la-path.lo libmio_la-pipe.lo libmio_la-pro.lo \
+	libmio_la-sck.lo libmio_la-skad.lo libmio_la-sys.lo \
+	libmio_la-sys-ass.lo libmio_la-sys-err.lo libmio_la-sys-log.lo \
+	libmio_la-sys-mux.lo libmio_la-sys-tim.lo libmio_la-thr.lo \
+	libmio_la-tmr.lo libmio_la-utf8.lo libmio_la-utl.lo \
+	libmio_la-utl-siph.lo $(am__objects_1)
 libmio_la_OBJECTS = $(am_libmio_la_OBJECTS)
 AM_V_lt = $(am__v_lt_@AM_V@)
 am__v_lt_ = $(am__v_lt_@AM_DEFAULT_V@)
@@ -206,9 +206,10 @@ am__depfiles_remade = ./$(DEPDIR)/libmio_la-chr.Plo \
 	./$(DEPDIR)/libmio_la-http.Plo ./$(DEPDIR)/libmio_la-json.Plo \
 	./$(DEPDIR)/libmio_la-mar-cli.Plo \
 	./$(DEPDIR)/libmio_la-mar.Plo ./$(DEPDIR)/libmio_la-mio.Plo \
-	./$(DEPDIR)/libmio_la-nwif.Plo ./$(DEPDIR)/libmio_la-path.Plo \
-	./$(DEPDIR)/libmio_la-pipe.Plo ./$(DEPDIR)/libmio_la-pro.Plo \
-	./$(DEPDIR)/libmio_la-sck.Plo ./$(DEPDIR)/libmio_la-skad.Plo \
+	./$(DEPDIR)/libmio_la-nwif.Plo ./$(DEPDIR)/libmio_la-opt.Plo \
+	./$(DEPDIR)/libmio_la-path.Plo ./$(DEPDIR)/libmio_la-pipe.Plo \
+	./$(DEPDIR)/libmio_la-pro.Plo ./$(DEPDIR)/libmio_la-sck.Plo \
+	./$(DEPDIR)/libmio_la-skad.Plo \
 	./$(DEPDIR)/libmio_la-sys-ass.Plo \
 	./$(DEPDIR)/libmio_la-sys-err.Plo \
 	./$(DEPDIR)/libmio_la-sys-log.Plo \
@@ -246,9 +247,9 @@ am__can_run_installinfo = \
   esac
 am__include_HEADERS_DIST = mio-cfg.h mio-chr.h mio-cmn.h mio-dns.h \
 	mio-ecs.h mio-fmt.h mio-htb.h mio-htrd.h mio-htre.h mio-http.h \
-	mio-json.h mio-nwif.h mio-pac1.h mio-path.h mio-pipe.h \
-	mio-pro.h mio-sck.h mio-skad.h mio-thr.h mio-upac.h mio-utl.h \
-	mio.h mio-mar.h
+	mio-json.h mio-nwif.h mio-opt.h mio-pac1.h mio-path.h \
+	mio-pipe.h mio-pro.h mio-sck.h mio-skad.h mio-thr.h mio-upac.h \
+	mio-utl.h mio.h mio-mar.h
 HEADERS = $(include_HEADERS)
 am__tagged_files = $(HEADERS) $(SOURCES) $(TAGS_FILES) $(LISP) \
 	mio-cfg.h.in
@@ -436,17 +437,17 @@ LIBADD_LIB_COMMON = $(LIBM)
 #pkgbindir = $(bindir)
 include_HEADERS = mio-cfg.h mio-chr.h mio-cmn.h mio-dns.h mio-ecs.h \
 	mio-fmt.h mio-htb.h mio-htrd.h mio-htre.h mio-http.h \
-	mio-json.h mio-nwif.h mio-pac1.h mio-path.h mio-pipe.h \
-	mio-pro.h mio-sck.h mio-skad.h mio-thr.h mio-upac.h mio-utl.h \
-	mio.h $(am__append_1)
+	mio-json.h mio-nwif.h mio-opt.h mio-pac1.h mio-path.h \
+	mio-pipe.h mio-pro.h mio-sck.h mio-skad.h mio-thr.h mio-upac.h \
+	mio-utl.h mio.h $(am__append_1)
 lib_LTLIBRARIES = libmio.la
 libmio_la_SOURCES = chr.c dns.c dns-cli.c ecs.c ecs-imp.h err.c fmt.c \
 	fmt-imp.h htb.c htrd.c htre.c http.c http-cgi.c http-fil.c \
 	http-prv.h http-svr.c http-thr.c http-txt.c json.c mio-prv.h \
-	mio.c nwif.c path.c pipe.c pro.c sck.c skad.c sys.c sys-ass.c \
-	sys-err.c sys-log.c sys-mux.c sys-prv.h sys-tim.c thr.c \
-	uch-case.h uch-prop.h tmr.c utf8.c utl.c utl-siph.c \
-	$(am__append_2)
+	mio.c nwif.c opt.c opt-imp.h path.c pipe.c pro.c sck.c skad.c \
+	sys.c sys-ass.c sys-err.c sys-log.c sys-mux.c sys-prv.h \
+	sys-tim.c thr.c uch-case.h uch-prop.h tmr.c utf8.c utl.c \
+	utl-siph.c $(am__append_2)
 libmio_la_CPPFLAGS = $(CPPFLAGS_LIB_COMMON)
 libmio_la_CFLAGS = $(CFLAGS_LIB_COMMON) $(am__append_3)
 libmio_la_LDFLAGS = $(LDFLAGS_LIB_COMMON) $(am__append_4)
@@ -566,6 +567,7 @@ distclean-compile:
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/libmio_la-mar.Plo@am__quote@ # am--include-marker
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/libmio_la-mio.Plo@am__quote@ # am--include-marker
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/libmio_la-nwif.Plo@am__quote@ # am--include-marker
+@AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/libmio_la-opt.Plo@am__quote@ # am--include-marker
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/libmio_la-path.Plo@am__quote@ # am--include-marker
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/libmio_la-pipe.Plo@am__quote@ # am--include-marker
 @AMDEP_TRUE@@am__include@ @am__quote@./$(DEPDIR)/libmio_la-pro.Plo@am__quote@ # am--include-marker
@@ -739,6 +741,13 @@ libmio_la-nwif.lo: nwif.c
 @AMDEP_TRUE@@am__fastdepCC_FALSE@	DEPDIR=$(DEPDIR) $(CCDEPMODE) $(depcomp) @AMDEPBACKSLASH@
 @am__fastdepCC_FALSE@	$(AM_V_CC@am__nodep@)$(LIBTOOL) $(AM_V_lt) --tag=CC $(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) --mode=compile $(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(libmio_la_CPPFLAGS) $(CPPFLAGS) $(libmio_la_CFLAGS) $(CFLAGS) -c -o libmio_la-nwif.lo `test -f 'nwif.c' || echo '$(srcdir)/'`nwif.c
 
+libmio_la-opt.lo: opt.c
+@am__fastdepCC_TRUE@	$(AM_V_CC)$(LIBTOOL) $(AM_V_lt) --tag=CC $(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) --mode=compile $(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(libmio_la_CPPFLAGS) $(CPPFLAGS) $(libmio_la_CFLAGS) $(CFLAGS) -MT libmio_la-opt.lo -MD -MP -MF $(DEPDIR)/libmio_la-opt.Tpo -c -o libmio_la-opt.lo `test -f 'opt.c' || echo '$(srcdir)/'`opt.c
+@am__fastdepCC_TRUE@	$(AM_V_at)$(am__mv) $(DEPDIR)/libmio_la-opt.Tpo $(DEPDIR)/libmio_la-opt.Plo
+@AMDEP_TRUE@@am__fastdepCC_FALSE@	$(AM_V_CC)source='opt.c' object='libmio_la-opt.lo' libtool=yes @AMDEPBACKSLASH@
+@AMDEP_TRUE@@am__fastdepCC_FALSE@	DEPDIR=$(DEPDIR) $(CCDEPMODE) $(depcomp) @AMDEPBACKSLASH@
+@am__fastdepCC_FALSE@	$(AM_V_CC@am__nodep@)$(LIBTOOL) $(AM_V_lt) --tag=CC $(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) --mode=compile $(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(libmio_la_CPPFLAGS) $(CPPFLAGS) $(libmio_la_CFLAGS) $(CFLAGS) -c -o libmio_la-opt.lo `test -f 'opt.c' || echo '$(srcdir)/'`opt.c
+
 libmio_la-path.lo: path.c
 @am__fastdepCC_TRUE@	$(AM_V_CC)$(LIBTOOL) $(AM_V_lt) --tag=CC $(AM_LIBTOOLFLAGS) $(LIBTOOLFLAGS) --mode=compile $(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(libmio_la_CPPFLAGS) $(CPPFLAGS) $(libmio_la_CFLAGS) $(CFLAGS) -MT libmio_la-path.lo -MD -MP -MF $(DEPDIR)/libmio_la-path.Tpo -c -o libmio_la-path.lo `test -f 'path.c' || echo '$(srcdir)/'`path.c
 @am__fastdepCC_TRUE@	$(AM_V_at)$(am__mv) $(DEPDIR)/libmio_la-path.Tpo $(DEPDIR)/libmio_la-path.Plo
@@ -1040,6 +1049,7 @@ distclean: distclean-am
 	-rm -f ./$(DEPDIR)/libmio_la-mar.Plo
 	-rm -f ./$(DEPDIR)/libmio_la-mio.Plo
 	-rm -f ./$(DEPDIR)/libmio_la-nwif.Plo
+	-rm -f ./$(DEPDIR)/libmio_la-opt.Plo
 	-rm -f ./$(DEPDIR)/libmio_la-path.Plo
 	-rm -f ./$(DEPDIR)/libmio_la-pipe.Plo
 	-rm -f ./$(DEPDIR)/libmio_la-pro.Plo
@@ -1122,6 +1132,7 @@ maintainer-clean: maintainer-clean-am
 	-rm -f ./$(DEPDIR)/libmio_la-mar.Plo
 	-rm -f ./$(DEPDIR)/libmio_la-mio.Plo
 	-rm -f ./$(DEPDIR)/libmio_la-nwif.Plo
+	-rm -f ./$(DEPDIR)/libmio_la-opt.Plo
 	-rm -f ./$(DEPDIR)/libmio_la-path.Plo
 	-rm -f ./$(DEPDIR)/libmio_la-pipe.Plo
 	-rm -f ./$(DEPDIR)/libmio_la-pro.Plo
diff --git a/mio/lib/mio-opt.h b/mio/lib/mio-opt.h
new file mode 100644
index 0000000..7570eed
--- /dev/null
+++ b/mio/lib/mio-opt.h
@@ -0,0 +1,141 @@
+/*
+ * $Id$
+ *
+    Copyright (c) 2016-2020 Chung, Hyung-Hwan. All rights reserved.
+
+    Redistribution and use in source and binary forms, with or without
+    modification, are permitted provided that the following conditions
+    are met:
+    1. Redistributions of source code must retain the above copyright
+       notice, this list of conditions and the following disclaimer.
+    2. Redistributions in binary form must reproduce the above copyright
+       notice, this list of conditions and the following disclaimer in the
+       documentation and/or other materials provided with the distribution.
+
+    THIS SOFTWARE IS PROVIDED BY THE AUTHOR "AS IS" AND ANY EXPRESS OR
+    IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+    OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+    IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+    NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+    DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+    THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+    (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+    THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _MIO_OPT_H_
+#define _MIO_OPT_H_
+
+#include "mio-cmn.h"
+
+/** \file
+ * This file defines functions and data structures to process 
+ * command-line arguments. 
+ */
+
+typedef struct mio_uopt_t mio_uopt_t;
+typedef struct mio_uopt_lng_t mio_uopt_lng_t;
+
+struct mio_uopt_lng_t
+{
+	const mio_uch_t* str;
+	mio_uci_t        val;
+};
+
+struct mio_uopt_t
+{
+	/* input */
+	const mio_uch_t* str; /* option string  */
+	mio_uopt_lng_t*  lng; /* long options */
+
+	/* output */
+	mio_uci_t        opt; /* character checked for validity */
+	mio_uch_t*       arg; /* argument associated with an option */
+
+	/* output */
+	const mio_uch_t* lngopt; 
+
+	/* input + output */
+	int              ind; /* index into parent argv vector */
+
+	/* input + output - internal*/
+	mio_uch_t*       cur;
+};
+
+typedef struct mio_bopt_t mio_bopt_t;
+typedef struct mio_bopt_lng_t mio_bopt_lng_t;
+
+struct mio_bopt_lng_t
+{
+	const mio_bch_t* str;
+	mio_bci_t        val;
+};
+
+struct mio_bopt_t
+{
+	/* input */
+	const mio_bch_t* str; /* option string  */
+	mio_bopt_lng_t*  lng; /* long options */
+
+	/* output */
+	mio_bci_t        opt; /* character checked for validity */
+	mio_bch_t*       arg; /* argument associated with an option */
+
+	/* output */
+	const mio_bch_t* lngopt; 
+
+	/* input + output */
+	int              ind; /* index into parent argv vector */
+
+	/* input + output - internal*/
+	mio_bch_t*       cur;
+};
+
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
+/**
+ * The mio_getopt() function processes the \a argc command-line arguments
+ * pointed to by \a argv as configured in \a opt. It can process two 
+ * different option styles: a single character starting with '-', and a 
+ * long name starting with '--'. 
+ *
+ * A character in \a opt.str is treated as a single character option. Should
+ * it require a parameter, specify ':' after it.
+ *
+ * Two special returning option characters indicate special error conditions. 
+ * - \b ? indicates a bad option stored in the \a opt->opt field.
+ * - \b : indicates a bad parameter for an option stored in the \a opt->opt field.
+ *
+ * @return an option character on success, MIO_CHAR_EOF on no more options.
+ */
+MIO_EXPORT mio_uci_t mio_getuopt (
+	int                argc, /* argument count */ 
+	mio_uch_t* const*  argv, /* argument array */
+	mio_uopt_t*        opt   /* option configuration */
+);
+
+MIO_EXPORT mio_bci_t mio_getbopt (
+	int                argc, /* argument count */ 
+	mio_bch_t* const*  argv, /* argument array */
+	mio_bopt_t*        opt   /* option configuration */
+);
+
+
+#if defined(MIO_OOCH_IS_UCH)
+#	define mio_opt_t mio_uopt_t
+#	define mio_opt_lng_t mio_uopt_lng_t
+#	define mio_getopt(argc,argv,opt) mio_getuopt(argc,argv,opt)
+#else
+#	define mio_opt_t mio_bopt_t
+#	define mio_opt_lng_t mio_bopt_lng_t
+#	define mio_getopt(argc,argv,opt) mio_getbopt(argc,argv,opt)
+#endif
+
+#if defined(__cplusplus)
+}
+#endif
+
+#endif
diff --git a/mio/lib/opt-imp.h b/mio/lib/opt-imp.h
new file mode 100644
index 0000000..24cf92e
--- /dev/null
+++ b/mio/lib/opt-imp.h
@@ -0,0 +1,215 @@
+/*
+ * $Id$
+ *
+    Copyright (c) 2016-2020 Chung, Hyung-Hwan. All rights reserved.
+
+    Redistribution and use in source and binary forms, with or without
+    modification, are permitted provided that the following conditions
+    are met:
+    1. Redistributions of source code must retain the above copyright
+       notice, this list of conditions and the following disclaimer.
+    2. Redistributions in binary form must reproduce the above copyright
+       notice, this list of conditions and the following disclaimer in the
+       documentation and/or other materials provided with the distribution.
+
+    THIS SOFTWARE IS PROVIDED BY THE AUTHOR "AS IS" AND ANY EXPRESS OR
+    IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+    OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+    IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+    NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+    DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+    THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+    (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+    THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+
+/* this file is supposed to be included by opt.c multiple times */
+
+
+#include "mio-opt.h"
+#include "mio-utl.h"
+
+/* 
+ * mio_getopt is based on BSD getopt.
+ * --------------------------------------------------------------------------
+ *
+ * Copyright (c) 1987-2002 The Regents of the University of California.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * A. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * B. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ * C. Neither the names of the copyright holders nor the names of its
+ *    contributors may be used to endorse or promote products derived from this
+ *    software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS
+ * IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ * --------------------------------------------------------------------------
+ */
+
+
+
+xci_t xgetopt (int argc, xch_t* const* argv, xopt_t* opt)
+{
+	xch_t* oli; /* option letter list index */
+	int dbldash = 0;
+
+	opt->arg = MIO_NULL;
+	opt->lngopt = MIO_NULL;
+
+	if (opt->cur == MIO_NULL) 
+	{
+		opt->cur = XEMSG;
+		opt->ind = 1;
+	}
+
+	if (*opt->cur == '\0') 
+	{
+		/* update scanning pointer */
+		if (opt->ind >= argc || *(opt->cur = argv[opt->ind]) != '-') 
+		{
+			/* All arguments have been processed or the current 
+			 * argument doesn't start with a dash */
+			opt->cur = XEMSG;
+			return XCI_EOF;
+		}
+
+		opt->cur++;
+
+	#if 0
+		if (*opt->cur == '\0')
+		{
+			/* - */
+			opt->ind++;
+			opt->cur = XEMSG;
+			return XCI_EOF;
+		}
+	#endif
+
+		if (*opt->cur == '-')
+		{
+			if (*++opt->cur == '\0')
+			{
+				/* -- */
+				opt->ind++;
+				opt->cur = XEMSG;
+				return XCI_EOF;
+			}
+			else
+			{
+				dbldash = 1;
+			}
+		}
+	}
+
+	if (dbldash && opt->lng != MIO_NULL)
+	{
+		const xopt_lng_t* o;
+		xch_t* end = opt->cur;
+
+		while (*end != '\0' && *end != '=') end++;
+
+		for (o = opt->lng; o->str; o++) 
+		{
+			const xch_t* str = o->str;
+
+			if (*str == ':') str++;
+
+			if (xcompcharscstr(opt->cur, end - opt->cur, str, 0) != 0) continue;
+
+			/* match */
+			opt->cur = XEMSG;
+			opt->lngopt = o->str;
+
+			/* for a long matching option, remove the leading colon */
+			if (opt->lngopt[0] == ':') opt->lngopt++;
+
+			if (*end == '=') opt->arg = end + 1;
+
+			if (*o->str != ':')
+			{
+				/* should not have an option argument */
+				if (opt->arg != MIO_NULL) return BADARG;
+			}
+			else if (opt->arg == MIO_NULL)
+			{
+				/* check if it has a remaining argument 
+				 * available */
+				if (argc <= ++opt->ind) return BADARG; 
+				/* If so, the next available argument is 
+				 * taken to be an option argument */
+				opt->arg = argv[opt->ind];
+			}
+
+			opt->ind++;
+			return o->val;
+		}
+
+		/*if (*end == MIO_T('=')) *end = MIO_T('\0');*/
+		opt->lngopt = opt->cur; 
+		return BADCH;
+	}
+
+	if ((opt->opt = *opt->cur++) == ':' ||
+	    (oli = xfindcharincstr(opt->str, opt->opt)) == MIO_NULL) 
+	{
+		/*
+		 * if the user didn't specify '-' as an option,
+		 * assume it means EOF.
+		 */
+		if (opt->opt == (int)'-') return XCI_EOF;
+		if (*opt->cur == '\0') ++opt->ind;
+		return BADCH;
+	}
+
+	if (*++oli != ':') 
+	{
+		/* don't need argument */
+		if (*opt->cur == '\0') opt->ind++;
+	}
+	else 
+	{
+		/* need an argument */
+
+		if (*opt->cur != '\0') 
+		{
+			/* no white space */
+			opt->arg = opt->cur;
+		}
+		else if (argc <= ++opt->ind) 
+		{
+			/* no arg */
+			opt->cur = XEMSG;
+			/*if (*opt->str == ':')*/ return BADARG;
+			/*return BADCH;*/
+		}
+		else
+		{
+			/* white space */
+			opt->arg = argv[opt->ind];
+		}
+
+		opt->cur = XEMSG;
+		opt->ind++;
+	}
+
+	return opt->opt;  /* dump back option letter */
+}
diff --git a/mio/lib/opt.c b/mio/lib/opt.c
new file mode 100644
index 0000000..51ed761
--- /dev/null
+++ b/mio/lib/opt.c
@@ -0,0 +1,82 @@
+/*
+ * $Id$
+ *
+    Copyright (c) 2016-2020 Chung, Hyung-Hwan. All rights reserved.
+
+    Redistribution and use in source and binary forms, with or without
+    modification, are permitted provided that the following conditions
+    are met:
+    1. Redistributions of source code must retain the above copyright
+       notice, this list of conditions and the following disclaimer.
+    2. Redistributions in binary form must reproduce the above copyright
+       notice, this list of conditions and the following disclaimer in the
+       documentation and/or other materials provided with the distribution.
+
+    THIS SOFTWARE IS PROVIDED BY THE AUTHOR "AS IS" AND ANY EXPRESS OR
+    IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+    OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+    IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+    NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+    DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+    THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+    (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+    THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "mio-opt.h"
+#include "mio-utl.h"
+
+#define BADCH   '?'
+#define BADARG  ':'
+
+static mio_uch_t EMSG_UCH[] = { '\0' };
+static mio_bch_t EMSG_BCH[] = { '\0' };
+
+/* ------------------------------------------------------------ */
+
+#undef XEMSG
+#undef xch_t
+#undef xci_t
+#undef xopt_t
+#undef xopt_lng_t
+#undef xgetopt
+#undef xcompcharscstr
+#undef xfindcharincstr
+#undef XCI_EOF
+
+#define XEMSG EMSG_UCH
+#define xch_t mio_uch_t
+#define xci_t mio_uci_t
+#define xopt_t mio_uopt_t
+#define xopt_lng_t mio_uopt_lng_t
+#define xgetopt mio_getuopt
+#define xcompcharscstr mio_comp_uchars_ucstr
+#define xfindcharincstr mio_find_uchar_in_ucstr
+#define XCI_EOF MIO_BCI_EOF
+#include "opt-imp.h"
+
+/* ------------------------------------------------------------ */
+
+#undef XEMSG
+#undef xch_t
+#undef xci_t
+#undef xopt_t
+#undef xopt_lng_t
+#undef xgetopt
+#undef xcompcharscstr
+#undef xfindcharincstr
+#undef XCI_EOF
+
+#define XEMSG EMSG_BCH
+#define xch_t mio_bch_t
+#define xci_t mio_bci_t
+#define xopt_t mio_bopt_t
+#define xopt_lng_t mio_bopt_lng_t
+#define xgetopt mio_getbopt
+#define xcompcharscstr mio_comp_bchars_bcstr
+#define xfindcharincstr mio_find_bchar_in_bcstr
+#define XCI_EOF MIO_UCI_EOF
+#include "opt-imp.h"
+
+/* ------------------------------------------------------------ */