diff --git a/passes/cmds/Makefile.inc b/passes/cmds/Makefile.inc
index 20b38bf8e..60f20fa6d 100644
--- a/passes/cmds/Makefile.inc
+++ b/passes/cmds/Makefile.inc
@@ -1,4 +1,5 @@
 
+OBJS += passes/cmds/exec.o
 OBJS += passes/cmds/add.o
 OBJS += passes/cmds/delete.o
 OBJS += passes/cmds/design.o
diff --git a/passes/cmds/exec.cc b/passes/cmds/exec.cc
new file mode 100644
index 000000000..399cb0ebb
--- /dev/null
+++ b/passes/cmds/exec.cc
@@ -0,0 +1,203 @@
+/*
+ *  yosys -- Yosys Open SYnthesis Suite
+ *
+ *  Copyright (C) 2012 - 2020  Claire Wolf <claire@symbioticeda.com>
+ *
+ *  Permission to use, copy, modify, and/or distribute this software for any
+ *  purpose with or without fee is hereby granted, provided that the above
+ *  copyright notice and this permission notice appear in all copies.
+ *
+ *  THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ *  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ *  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ *  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ *  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ *  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ *  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ */
+
+#include "kernel/register.h"
+#include "kernel/log.h"
+#include <cstdio>
+
+#if defined(_WIN32)
+#  define WIFEXITED(x) 1
+#  define WIFSIGNALED(x) 0
+#  define WIFSTOPPED(x) 0
+#  define WEXITSTATUS(x) ((x) & 0xff)
+#  define WTERMSIG(x) SIGTERM
+#else
+#  include <sys/wait.h>
+#endif
+
+USING_YOSYS_NAMESPACE
+PRIVATE_NAMESPACE_BEGIN
+
+struct ExecPass : public Pass {
+	ExecPass() : Pass("exec", "execute commands in the operating system shell") { }
+	void help() YS_OVERRIDE
+	{
+		//   |---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|---v---|
+		log("\n");
+		log("    exec [options] -- [command]\n");
+		log("\n");
+		log("Execute a command in the operating system shell.  All supplied arguments are\n");
+		log("concatenated and passed as a command to popen(3).  Whitespace is not guaranteed\n");
+		log("to be preserved, even if quoted.  stdin and stderr are not connected, while stdout is\n");
+		log("logged unless the \"-q\" option is specified.\n");
+		log("\n");
+		log("\n");
+		log("    -q\n");
+		log("        Suppress stdout and stderr from subprocess\n");
+		log("\n");
+		log("    -expect-return <int>\n");
+		log("        Generate an error if popen() does not return specified value.\n");
+		log("        May only be specified once; the final specified value is controlling\n");
+		log("        if specified multiple times.\n");
+		log("\n");
+		log("    -expect-stdout <regex>\n");
+		log("        Generate an error if the specified regex does not match any line\n");
+		log("        in subprocess's stdout.  May be specified multiple times.\n");
+		log("\n");
+		log("    -not-expect-stdout <regex>\n");
+		log("        Generate an error if the specified regex matches any line\n");
+		log("        in subprocess's stdout.  May be specified multiple times.\n");
+		log("\n");
+		log("\n");
+		log("    Example: exec -q -expect-return 0 -- echo \"bananapie\" | grep \"nana\"\n");
+		log("\n");
+		log("\n");
+	}
+	void execute(std::vector<std::string> args, RTLIL::Design *design) YS_OVERRIDE
+	{
+		std::string cmd = "";
+		char buf[1024] = {};
+		std::string linebuf = "";
+		bool flag_cmd = false;
+		bool flag_quiet = false;
+		bool flag_expect_return = false;
+		int expect_return_value = 0;
+		bool flag_expect_stdout = false;
+		struct expect_stdout_elem {
+			bool matched;
+			bool polarity;	//true: this regex must match at least one line
+					//false: this regex must not match any line
+			std::string str;
+			YS_REGEX_TYPE re;
+
+			expect_stdout_elem() : matched(false), polarity(true), str(), re(){};
+		};
+		std::vector<expect_stdout_elem> expect_stdout;
+
+		if(args.size() == 0)
+			log_cmd_error("No command provided.\n");
+
+		for(size_t argidx = 1; argidx < args.size(); ++argidx) {
+			if (flag_cmd) {
+				cmd += args[argidx] + (argidx != (args.size() - 1)? " " : "");
+			} else {
+				if (args[argidx] == "--")
+					flag_cmd = true;
+				else if (args[argidx] == "-q")
+					flag_quiet = true;
+				else if (args[argidx] == "-expect-return") {
+					flag_expect_return = true;
+					++argidx;
+					if (argidx >= args.size())
+						log_cmd_error("No expected return value specified.\n");
+
+					expect_return_value = atoi(args[argidx].c_str());
+				} else if (args[argidx] == "-expect-stdout") {
+					flag_expect_stdout = true;
+					++argidx;
+					if (argidx >= args.size())
+						log_cmd_error("No expected regular expression specified.\n");
+
+					try{
+						expect_stdout_elem x;
+						x.str = args[argidx];
+						x.re = YS_REGEX_COMPILE(args[argidx]);
+						expect_stdout.push_back(x);
+					} catch (const YS_REGEX_NS::regex_error& e) {
+						log_cmd_error("Error in regex expression '%s' !\n", args[argidx].c_str());
+					}
+				} else if (args[argidx] == "-not-expect-stdout") {
+					flag_expect_stdout = true;
+					++argidx;
+					if (argidx >= args.size())
+						log_cmd_error("No expected regular expression specified.\n");
+
+					try{
+						expect_stdout_elem x;
+						x.str = args[argidx];
+						x.re = YS_REGEX_COMPILE(args[argidx]);
+						x.polarity = false;
+						expect_stdout.push_back(x);
+					} catch (const YS_REGEX_NS::regex_error& e) {
+						log_cmd_error("Error in regex expression '%s' !\n", args[argidx].c_str());
+					}
+
+				} else
+					log_cmd_error("Unknown option \"%s\" or \"--\" doesn\'t precede command.", args[argidx].c_str());
+			}
+		}
+
+		log_header(design, "Executing command \"%s\".\n", cmd.c_str());
+		log_push();
+
+		fflush(stdout);
+		bool keep_reading = true;
+		int status = 0;
+		int retval = 0;
+
+#ifndef EMSCRIPTEN
+		FILE *f = popen(cmd.c_str(), "r");
+		if (f == nullptr)
+			log_cmd_error("errno %d after popen() returned NULL.\n", errno);
+		while (keep_reading) {
+			keep_reading = (fgets(buf, sizeof(buf), f) != nullptr);
+			linebuf += buf;
+			memset(buf, 0, sizeof(buf));
+
+			auto pos = linebuf.find('\n');
+			while (pos != std::string::npos) {
+				std::string line = linebuf.substr(0, pos);
+				linebuf.erase(0, pos + 1);
+				if (!flag_quiet)
+					log("%s\n", line.c_str());
+
+				if (flag_expect_stdout)
+					for(auto &x : expect_stdout)
+						if (YS_REGEX_NS::regex_search(line, x.re))
+							x.matched = true;
+
+				pos = linebuf.find('\n');
+			}
+		}
+		status = pclose(f);
+#endif
+
+		if(WIFEXITED(status)) {
+		    retval = WEXITSTATUS(status);
+		}
+		else if(WIFSIGNALED(status)) {
+		    retval = WTERMSIG(status);
+		}
+		else if(WIFSTOPPED(status)) {
+		    retval = WSTOPSIG(status);
+		}
+
+		if (flag_expect_return && retval != expect_return_value)
+			log_cmd_error("Return value %d did not match expected return value %d.\n", retval, expect_return_value);
+
+		if (flag_expect_stdout)
+			for (auto &x : expect_stdout)
+				if (x.polarity ^ x.matched)
+					log_cmd_error("Command stdout did%s have a line matching given regex \"%s\".\n", (x.polarity? " not" : ""), x.str.c_str());
+
+		log_pop();
+	}
+} ExecPass;
+
+PRIVATE_NAMESPACE_END
diff --git a/tests/various/exec.ys b/tests/various/exec.ys
new file mode 100644
index 000000000..0eec00719
--- /dev/null
+++ b/tests/various/exec.ys
@@ -0,0 +1,6 @@
+exec -expect-return 0 -- exit 0
+exec -expect-return 27 -- exit 27
+exec -expect-stdout nana -expect-stdout api -not-expect-stdout giraffe -- echo "bananapie"
+
+logger -expect error "stdout did have a line" 1
+exec -not-expect-stdout giraffe -- echo "giraffe"