diff --git a/CMakeLists.txt b/CMakeLists.txt
index b5f3a75..21ebd87 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -110,7 +110,7 @@ endif()
 
 
 add_executable(mpw-shell mpw-shell.cpp  mpw-shell-token.cpp mpw-shell-expand.cpp 
-	mpw-shell-parser.cpp mpw_parser.cpp value.cpp mpw-shell-quote.cpp 
+	mpw-shell-parser.cpp mpw_parser.cpp value.cpp mpw-shell-quote.cpp mpw-regex.cpp
 	phase1.cpp phase2.cpp phase3.cpp command.cpp environment.cpp builtins.cpp 
 	pathnames.cpp
 	macroman.cpp
diff --git a/builtins.cpp b/builtins.cpp
index 2da1968..5dbdaaf 100644
--- a/builtins.cpp
+++ b/builtins.cpp
@@ -691,7 +691,7 @@ int builtin_evaluate(Environment &env, std::vector<token> &&tokens, const fdmask
 			tokens.pop_back();
 			tokens.pop_back();
 
-			int32_t i = evaluate_expression("Evaluate", std::move(tokens));
+			int32_t i = evaluate_expression(env, "Evaluate", std::move(tokens));
 
 			switch(type) {
 				case '=':
@@ -721,7 +721,7 @@ int builtin_evaluate(Environment &env, std::vector<token> &&tokens, const fdmask
 		}
 	}
 
-	int32_t i = evaluate_expression("Evaluate", std::move(tokens));
+	int32_t i = evaluate_expression(env, "Evaluate", std::move(tokens));
 
 	if (output == 'h') {
 		fdprintf(stdout, "0x%08x\n", i);
diff --git a/command.cpp b/command.cpp
index d95d6c2..7c88fd1 100644
--- a/command.cpp
+++ b/command.cpp
@@ -101,7 +101,7 @@ namespace {
 			case IF:
 				tokens.pop_back();
 				try {
-					e = evaluate_expression("If", std::move(tokens));
+					e = evaluate_expression(env, "If", std::move(tokens));
 				}
 				catch (std::exception &ex) {
 					fprintf(stderr, "%s\n", ex.what());
diff --git a/error.h b/error.h
index ec7326b..486b072 100644
--- a/error.h
+++ b/error.h
@@ -81,6 +81,13 @@ public:
 	{}
 };
 
+class regex_error : public mpw_error {
+public:
+	regex_error(int status = -2) :
+		mpw_error(status, "MPW Shell - File name pattern is incorrect")
+		{}
+
+};
 
 /*
   these are used for flow-control.
diff --git a/mpw-regex.cpp b/mpw-regex.cpp
new file mode 100644
index 0000000..364177b
--- /dev/null
+++ b/mpw-regex.cpp
@@ -0,0 +1,269 @@
+
+#include "mpw-regex.h"
+#include "environment.h"
+
+typedef std::string::const_iterator iterator;
+
+namespace {
+	bool ecma_special(unsigned char c) {
+		//
+		switch(c) {
+		case '|':
+		case '{':
+		case '}':
+		case '(':
+		case ')':
+		case '[':
+		case ']':
+		case '*':
+		case '+':
+		case '^':
+		case '$':
+		case '.':
+		case '\\':
+			return true;
+		default:
+			return false;
+		}
+	}
+}
+
+mpw_regex::mpw_regex(const std::string &s, bool slash) {
+	convert_re(s, slash);
+}
+
+bool mpw_regex::is_glob(const std::string &s) {
+	bool esc = false;
+	for (unsigned char c : s) {
+		if (esc) {
+			esc = false;
+			continue;
+		}
+		switch(c) {
+		case 0xb6:
+			esc = true;
+			break;
+		case '[':
+		case '?':
+		case '*':
+		case '+':
+		case 0xc7:
+		case 0xc5:
+			return true;
+		default:
+			break;
+		}
+	}
+	return false;
+}
+
+bool mpw_regex::match(const std::string &s, Environment &e) {
+	 std::smatch m;
+	bool ok = std::regex_match(s, m, re);
+	if (!ok) return false;
+
+	for (int i = 0; i < 10; ++i) {
+		int index = capture_map[i];
+
+		if (index && index < m.size() && m[index].matched) {
+			std::string v(m[index].first, m[index].second);
+			std::string k("\xa8");
+			k += (i + '0');
+			e.set(k, std::move(v));
+		}
+	}
+
+	return true;
+}
+
+bool mpw_regex::match(const std::string &s) {
+	return std::regex_match(s, re);
+}
+
+
+// convert a mpw-flavor regex to std::regex flavor regex.
+void mpw_regex::convert_re(const std::string &s, bool slash) {
+
+
+	std::string accumulator;
+	auto iter = s.begin();
+	auto end = s.end();
+
+	if (slash) {
+		if (iter == end || *iter++ != '/')
+			throw std::regex_error(std::regex_constants::error_space);
+	}
+
+	iter = convert_re(iter, end, accumulator, slash ? '/' : 0);
+
+	if (iter != end) throw std::regex_error(std::regex_constants::error_space);
+
+
+	re = std::regex(accumulator);
+	if (slash) key = s;
+	else key = "/" + s + "/";
+}
+
+
+iterator mpw_regex::convert_re(iterator iter, iterator end, std::string &accumulator, unsigned char term) {
+
+	while (iter != end) {
+		unsigned char c = *iter++;
+		if (c == 0xb6) {
+			// escape
+			if (iter == end) throw std::regex_error(std::regex_constants::error_escape);
+			c = *iter++;
+			if (ecma_special(c))
+				accumulator += '\\';
+			accumulator += c;
+			continue;
+		}
+		if (term && c == term) {
+			return iter;
+		}
+		if (c == '?') {
+			// match any char
+			accumulator += '.';
+			continue;
+		}
+		if (c == 0xc5) {
+			// match any string
+			accumulator += ".*";
+			continue;
+		}
+		if (c == '[') {
+			// begin a set
+			iter = convert_re_set(iter, end, accumulator);
+			continue;
+		}
+		if (c == '(') {
+			// begin a capture
+			iter = convert_re_capture(iter, end, accumulator);
+			continue;
+		}
+		if (c == 0xc7) {
+			// repeat
+			iter = convert_re_repeat(iter, end, accumulator);
+			continue;
+		}
+		if (c == '+' || c == '*') {
+			// same meaning
+			accumulator += c;
+			continue;
+		}
+		if (ecma_special(c)) {
+			accumulator += '\\';
+		}
+		accumulator += c;
+	}
+
+	if (term) throw std::regex_error(std::regex_constants::error_paren);
+	return iter;
+}
+
+iterator mpw_regex::convert_re_repeat(iterator iter, iterator end, std::string &accumulator) {
+	int min = -1;
+	int max = -1;
+
+	accumulator += "{";
+
+	while (iter != end) {
+		unsigned char c = *iter++;
+		if (c == 0xc8) {
+			accumulator += "}";
+			return iter;			
+		}
+		if (c != ',' && !isdigit(c)) break;
+		accumulator += c;
+	}
+	throw std::regex_error(std::regex_constants::error_brace);
+}
+
+iterator mpw_regex::convert_re_set(iterator iter, iterator end, std::string &accumulator) {
+	// need extra logic to block character classes.
+
+	unsigned char c;
+	accumulator += "[";
+
+	if (iter != end && static_cast<unsigned char>(*iter) == 0xc2) {
+		accumulator += "^";
+		++iter;
+	} else if (iter != end && *iter == '^') {
+		// leading ^ needs to be escaped.
+		accumulator += "\\^";
+		++iter;
+	}
+	while (iter != end) {
+		c = *iter++;
+
+		if (c == 0xb6) {
+			// escape
+			if (iter == end) throw std::regex_error(std::regex_constants::error_escape);
+			c = *iter++;
+			accumulator += '\\';
+			accumulator += c;
+			continue;
+		}
+
+		if (c == ']') {
+			accumulator += "]";
+			return iter;
+		}
+		if (c == '\\') {
+			accumulator += "\\\\";
+			continue;
+		}
+		accumulator += c;
+	}
+
+	throw std::regex_error(std::regex_constants::error_brack);
+}
+
+iterator mpw_regex::convert_re_capture(iterator iter, iterator end, std::string &accumulator) {
+
+
+	/*
+	 * consider: (abc(abc)®1(xyz))®2
+	 * m[1] = (abcabcxyz)
+	 * m[2] = (abc)
+	 * BUT we don't know if it's captured until the ® is parsed.
+	 */
+
+	std::string scratch;
+	bool capture = false;
+	int n = -1;
+
+	int ecma_index = ++num_captures;
+
+	if (iter != end && *iter == '?') {
+		// leading ? needs to be escaped.
+		scratch += "\\?";
+		++iter;
+	}
+	iter = convert_re(iter, end, scratch, ')');
+
+	// check for capture?
+	if (iter != end && static_cast<unsigned char>(*iter) == 0xa8) {
+		++iter;
+		if (iter == end || !isdigit(*iter))
+			throw std::regex_error(std::regex_constants::error_badbrace); // eh
+		n = *iter++ - '0';
+		capture = true;
+	}
+
+	accumulator += '(';
+	if (capture) {
+		/// ummm capture within a capture? backwards?
+		capture_map[n] = ecma_index;
+	} else {
+		accumulator += "?:";
+		// re-number all sub-captures.
+		--num_captures;
+		for (int &index : capture_map) {
+			if (index >= ecma_index) --index;
+		} 
+	}
+	accumulator += scratch;
+	accumulator += ')';
+	return iter;
+}
diff --git a/mpw-regex.h b/mpw-regex.h
new file mode 100644
index 0000000..5893629
--- /dev/null
+++ b/mpw-regex.h
@@ -0,0 +1,48 @@
+#ifndef __mpw_regex_h__
+#define __mpw_regex_h__
+
+#include "environment.h"
+
+#include <string>
+#include <regex>
+
+class mpw_regex {
+
+public:
+
+	mpw_regex(const std::string &s, bool slash);
+
+	mpw_regex(const mpw_regex &) = default;
+	// mpw_regex(mpw_regex &&) = default;
+
+	~mpw_regex() = default;
+
+
+	mpw_regex &operator=(const mpw_regex &) = default;
+	// mpw_regex &operator=(mpw_regex &&) = default;
+
+	bool match(const std::string &, class Environment &);
+	bool match(const std::string &);
+
+	static bool is_glob(const std::string &s);
+
+private:
+	typedef std::string::const_iterator iterator;
+
+
+	void convert_re(const std::string &, bool slash);
+
+	iterator convert_re(iterator iter, iterator end, std::string &accumulator, unsigned char term);
+	iterator convert_re_repeat(iterator iter, iterator end, std::string &accumulator);
+	iterator convert_re_set(iterator iter, iterator end, std::string &accumulator);
+	iterator convert_re_capture(iterator iter, iterator end, std::string &accumulator);
+
+
+	std::regex re;
+	std::string key;
+	int capture_map[10] = {}; // map mpw capture number to ecma group
+	int num_captures = 0;
+
+};
+
+#endif
diff --git a/mpw-shell-expand.rl b/mpw-shell-expand.rl
index d67f8b5..74508ef 100644
--- a/mpw-shell-expand.rl
+++ b/mpw-shell-expand.rl
@@ -80,12 +80,18 @@
 
 
 	escape = 0xb6;
-	char = any - escape - ['"{`];
+	char = any - escape - ['"{`/\\];
 	escape_seq = escape any;
 
 	schar = [^'];
 	sstring = ['] schar** ['];
 
+	fchar = [^/];
+	fstring = [/] fchar** [/];
+
+	bchar = [^\\];
+	bstring = [\\] bchar** [\\];
+
 
 	vchar = [^}] $vpush;
 	vchar1 = [^{}] $vpush;
@@ -114,6 +120,8 @@
 	main := (
 		  escape_seq $push
 		| sstring $push
+		| fstring $push
+		| bstring $push
 		| dstring $push
 		| vstring
 		| estring
diff --git a/mpw-shell-parser.cpp b/mpw-shell-parser.cpp
index 88d4ffa..8556c01 100644
--- a/mpw-shell-parser.cpp
+++ b/mpw-shell-parser.cpp
@@ -2,6 +2,7 @@
 #include "fdset.h"
 #include "value.h"
 #include "error.h"
+#include "mpw-regex.h"
 
 #include <unistd.h>
 #include <fcntl.h>
@@ -172,8 +173,8 @@ class expression_parser {
 
 public:
 
-	expression_parser(const std::string &n, std::vector<token> &&t) : 
-		name(n), tokens(std::move(t))
+	expression_parser(Environment &e, const std::string &n, std::vector<token> &&t) : 
+		environment(e),	name(n), tokens(std::move(t))
 	{}
 
 	expression_parser(const expression_parser &) = delete;
@@ -194,6 +195,7 @@ private:
 
 
 	value eval(int op, value &lhs, value &rhs);
+	value eval_regex(value &lhs, value &rhs);
 
 	[[noreturn]] void expect_binary_operator();
 	[[noreturn]] void end_of_expression();
@@ -207,6 +209,7 @@ private:
 		if (!tokens.empty()) tokens.pop_back();
 	}
 
+	Environment &environment;
 	const std::string &name;
 	std::vector<token> tokens;
 };
@@ -323,8 +326,8 @@ int expression_parser::precedence(int op) {
 
 		case '==':
 		case '!=':
-		case token::equivalent:
-		case token::not_equivalent:
+		case '=~':
+		case '!~':
 			return 7;
 		case '&':
 			return 8;
@@ -341,6 +344,25 @@ int expression_parser::precedence(int op) {
 	//throw std::runtime_error("unimplemented op";);
 }
 
+value expression_parser::eval_regex(value &lhs, value &rhs) {
+	try {
+		mpw_regex re(rhs.string, true);
+		// todo -- need environment to store matches.
+		bool ok = re.match(lhs.string, environment);
+		return ok ? 1 : 0;
+
+	} catch (std::exception &ex) {
+		std::string error;
+		error = name;
+		if (rhs.string.empty() || rhs.string.front() != '/')
+			error += " - Missing /s around regular expression: ";
+		else
+			error += " - Invalid regular expression encountered: ";
+		error += rhs.string;
+		throw mpw_error(-5, error);
+	}
+}
+
 value expression_parser::eval(int op, value &lhs, value &rhs) {
 	switch (op) {
 
@@ -407,6 +429,12 @@ value expression_parser::eval(int op, value &lhs, value &rhs) {
 			return lhs.string != rhs.string;
 
 
+		case '=~':
+			return eval_regex(lhs, rhs);
+
+		case '!~':
+			return !eval_regex(lhs, rhs).number;
+
 	}
 	// todo...
 	throw std::runtime_error("unimplemented op");
@@ -469,8 +497,8 @@ int32_t expression_parser::evaluate() {
 	return v.to_number(1);
 }
 
-int32_t evaluate_expression(const std::string &name, std::vector<token> &&tokens) {
+int32_t evaluate_expression(Environment &env, const std::string &name, std::vector<token> &&tokens) {
 
-	expression_parser p(name, std::move(tokens));
+	expression_parser p(env, name, std::move(tokens));
 	return p.evaluate();
 }
diff --git a/mpw-shell-token.rl b/mpw-shell-token.rl
index 0a6d5c3..80c9106 100644
--- a/mpw-shell-token.rl
+++ b/mpw-shell-token.rl
@@ -38,19 +38,21 @@
 	dstring = ["] dchar** ["] $err{ throw dstring_error(); } ;
 
 	# search-forward string
-	fschar = escape_seq | (any - escape - [/]);
-	fsstring = [/] fschar** [/] $err{ throw fsstring_error(); } ;
+	# fschar = escape_seq | (any - escape - [/]);
+	fchar = [^/];
+	fstring = [/] fchar** [/] $err{ throw fsstring_error(); } ;
 
 	# search-backward string
-	bschar = escape_seq | (any - escape - [\\]);
-	bsstring = [\\] bschar** [\\] $err{ throw bsstring_error(); } ;
+	# bschar = escape_seq | (any - escape - [\\]);
+	bchar = [^\\];
+	bstring = [\\] bchar** [\\] $err{ throw bsstring_error(); } ;
 
 	action eval { eval }
 
 	# > == start state (single char tokens or common prefix)
 	# % == final state (multi char tokens w/ unique prefix)
 	# $ == all states
-	char = any - ['"];
+	char = any - ['"/\\];
 	main := |*
 			ws+  >push_token;
 			'>>' %push_token => { tokens.emplace_back(">>", '>>'); };
@@ -142,8 +144,8 @@
 
 			sstring => push_string;
 			dstring => push_string;
-			fsstring => push_string;
-			bsstring => push_string;
+			fstring => push_string;
+			bstring => push_string;
 			escape_seq => push_string;
 
 			char => push;
@@ -202,11 +204,19 @@ void unquote(token &t) {
 
 	action push { scratch.push_back(fc); }
 	escape = 0xb6;
-	char = any - escape - ['"];
+	char = any - escape - ['"/\\];
 
 	schar = [^'] $push;
 	sstring = ['] schar** ['];
 
+	# // and \\ strings retain the delimiter.
+	fchar = [^/];
+	fstring = ([/] fchar** [/]) $push;
+
+	bchar = [^\\];
+	bstring = ([\\] bchar** [\\]) $push;
+
+
 	ecode = 
 		  'f' ${ scratch.push_back('\f'); }
 		| 'n' ${ scratch.push_back('\n'); }
@@ -222,6 +232,8 @@ void unquote(token &t) {
 	main := (
 		  escape_seq
 		| sstring
+		| fstring
+		| bstring
 		| dstring
 		| char $push
 	)**;
diff --git a/mpw-shell.h b/mpw-shell.h
index c87df4a..a9126be 100644
--- a/mpw-shell.h
+++ b/mpw-shell.h
@@ -64,7 +64,7 @@ void parse_tokens(std::vector<token> &&tokens, process &p);
 
 
 
-int32_t evaluate_expression(const std::string &name, std::vector<token> &&tokens);
+int32_t evaluate_expression(Environment &e, const std::string &name, std::vector<token> &&tokens);
 
 
 
diff --git a/phase1.cpp b/phase1.cpp
index 32a50d6..7048bdf 100644
--- a/phase1.cpp
+++ b/phase1.cpp
@@ -25,6 +25,13 @@ enum {
 	st_estring2_esc,
 
 	st_estring3,
+
+	st_fstring,
+	st_fstring_esc,
+
+	st_bstring,
+	st_bstring_esc,
+
 };
 
 
@@ -54,6 +61,8 @@ int phase1::process(unsigned char c, int st) {
 		case st_sstring_esc:
 		case st_estring1_esc:
 		case st_estring2_esc:
+		case st_fstring_esc:
+		case st_bstring_esc:
 			multiline = true;
 			scratch.pop_back();
 			line++;
@@ -81,6 +90,10 @@ text:
 					return st_sstring;
 				case '`':
 					return st_estring;
+				case '/':
+					return st_fstring;
+				case '\\':
+					return st_bstring;
 
 				default:
 					return st_text;
@@ -109,6 +122,23 @@ text:
 			return st_sstring;
 			break;
 
+
+		case st_fstring_esc:
+			// fall through
+		case st_fstring:
+			if (c == '/') return st_text;
+			if (c == esc) return st_fstring_esc;
+			return st_fstring;
+			break;
+
+		case st_bstring_esc:
+			// fall through
+		case st_bstring:
+			if (c == '\\') return st_text;
+			if (c == esc) return st_bstring_esc;
+			return st_bstring;
+			break;
+
 		case st_dstring:
 			if (c == '\"') return st_text;
 			if (c == esc) return st_dstring_esc;
diff --git a/phase2.rl b/phase2.rl
index 647affa..bad23f7 100644
--- a/phase2.rl
+++ b/phase2.rl
@@ -86,6 +86,13 @@
 	schar = [^'];
 	sstring = ['] schar** ['] ;
 
+	fchar = [^/];
+	fstring = [/] fchar** [/] ;
+
+	bchar = [^\\];
+	bstring = [\\] bchar** [\\] ;
+
+
 	vchar = [^}];
 	vstring = [{] vchar** [}] ;
 
@@ -112,6 +119,8 @@
 		| '&' '&' $parse_amp_amp
 		| escape_seq
 		| sstring
+		| fstring
+		| bstring
 		| dstring
 		| vstring
 		| estring