diff --git a/libexec/flua/modules/lposix.c b/libexec/flua/modules/lposix.c
index 47a1354aede9..43b9ee83673c 100644
--- a/libexec/flua/modules/lposix.c
+++ b/libexec/flua/modules/lposix.c
@@ -1,579 +1,613 @@
 /*-
  * Copyright (c) 2019, 2023 Kyle Evans <kevans@FreeBSD.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
 #include <sys/stat.h>
 #include <sys/utsname.h>
 #include <sys/wait.h>
 
 #include <errno.h>
 #include <fnmatch.h>
 #include <grp.h>
 #include <libgen.h>
 #include <pwd.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
 
 #include <lua.h>
 #include "lauxlib.h"
 #include "lposix.h"
 
 static void
 enforce_max_args(lua_State *L, int max)
 {
 	int narg;
 
 	narg = lua_gettop(L);
 	luaL_argcheck(L, narg <= max, max + 1, "too many arguments");
 }
 
 /*
  * Minimal implementation of luaposix needed for internal FreeBSD bits.
  */
 static int
 lua__exit(lua_State *L)
 {
 	int code;
 
 	enforce_max_args(L, 1);
 	code = luaL_checkinteger(L, 1);
 
 	_exit(code);
 }
 
 static int
 lua_basename(lua_State *L)
 {
 	char *inpath, *outpath;
 
 	enforce_max_args(L, 1);
 	inpath = strdup(luaL_checkstring(L, 1));
 	if (inpath == NULL) {
 		lua_pushnil(L);
 		lua_pushstring(L, strerror(ENOMEM));
 		lua_pushinteger(L, ENOMEM);
 		return (3);
 	}
 
 	outpath = basename(inpath);
 	lua_pushstring(L, outpath);
 	free(inpath);
 	return (1);
 }
 
 static int
 lua_chmod(lua_State *L)
 {
 	const char *path;
 	mode_t mode;
 
 	enforce_max_args(L, 2);
 	path = luaL_checkstring(L, 1);
 	mode = (mode_t)luaL_checkinteger(L, 2);
 
 	if (chmod(path, mode) == -1) {
 		lua_pushnil(L);
 		lua_pushstring(L, strerror(errno));
 		lua_pushinteger(L, errno);
 		return (3);
 	}
 	lua_pushinteger(L, 0);
 	return (1);
 }
 
 static int
 lua_chown(lua_State *L)
 {
 	const char *path;
 	uid_t owner = (uid_t)-1;
 	gid_t group = (gid_t)-1;
 	int error;
 
 	enforce_max_args(L, 3);
 
 	path = luaL_checkstring(L, 1);
 	if (lua_isinteger(L, 2))
 		owner = (uid_t)lua_tointeger(L, 2);
 	else if (lua_isstring(L, 2)) {
 		char buf[4096];
 		struct passwd passwd, *pwd;
 
 		error = getpwnam_r(lua_tostring(L, 2), &passwd,
 		    buf, sizeof(buf), &pwd);
 		if (error == 0)
 			owner = pwd->pw_uid;
 		else
 			return (luaL_argerror(L, 2,
 			    lua_pushfstring(L, "unknown user %s",
 			    lua_tostring(L, 2))));
 	} else if (!lua_isnoneornil(L, 2)) {
 		const char *type = luaL_typename(L, 2);
 		return (luaL_argerror(L, 2,
 		    lua_pushfstring(L, "integer or string expected, got %s",
 		    type)));
 	}
 
 	if (lua_isinteger(L, 3))
 		group = (gid_t)lua_tointeger(L, 3);
 	else if (lua_isstring(L, 3)) {
 		char buf[4096];
 		struct group gr, *grp;
 
 		error = getgrnam_r(lua_tostring(L, 3), &gr, buf, sizeof(buf),
 		    &grp);
 		if (error == 0)
 			group = grp->gr_gid;
 		else
 			return (luaL_argerror(L, 3,
 			    lua_pushfstring(L, "unknown group %s",
 			    lua_tostring(L, 3))));
 	} else if (!lua_isnoneornil(L, 3)) {
 		const char *type = luaL_typename(L, 3);
 		return (luaL_argerror(L, 3,
 		    lua_pushfstring(L, "integer or string expected, got %s",
 		    type)));
 	}
 
 	if (chown(path, owner, group) == -1) {
 		lua_pushnil(L);
 		lua_pushstring(L, strerror(errno));
 		lua_pushinteger(L, errno);
 		return (3);
 	}
 	lua_pushinteger(L, 0);
 	return (1);
 }
 
 static int
 lua_pclose(lua_State *L)
 {
 	int error, fd;
 
 	enforce_max_args(L, 1);
 
 	fd = luaL_checkinteger(L, 1);
 	if (fd < 0) {
 		error = EBADF;
 		goto err;
 	}
 
 	if (close(fd) == 0) {
 		lua_pushinteger(L, 0);
 		return (1);
 	}
 
 	error = errno;
 err:
 	lua_pushnil(L);
 	lua_pushstring(L, strerror(error));
 	lua_pushinteger(L, error);
 	return (3);
 
 }
 
+static int
+lua_dup2(lua_State *L)
+{
+	int error, oldd, newd;
+
+	enforce_max_args(L, 2);
+
+	oldd = luaL_checkinteger(L, 1);
+	if (oldd < 0) {
+		error = EBADF;
+		goto err;
+	}
+
+	newd = luaL_checkinteger(L, 2);
+	if (newd < 0) {
+		error = EBADF;
+		goto err;
+	}
+
+	error = dup2(oldd, newd);
+	if (error >= 0) {
+		lua_pushinteger(L, error);
+		return (1);
+	}
+
+	error = errno;
+err:
+	lua_pushnil(L);
+	lua_pushstring(L, strerror(error));
+	lua_pushinteger(L, error);
+	return (3);
+}
+
 static int
 lua_fnmatch(lua_State *L)
 {
 	const char *pattern, *string;
 	int flags;
 
 	enforce_max_args(L, 3);
 	pattern = luaL_checkstring(L, 1);
 	string = luaL_checkstring(L, 2);
 	flags = luaL_optinteger(L, 3, 0);
 
 	lua_pushinteger(L, fnmatch(pattern, string, flags));
 
 	return (1);
 }
 
 static int
 lua_uname(lua_State *L)
 {
 	struct utsname name;
 	int error;
 
 	enforce_max_args(L, 0);
 
 	error = uname(&name);
 	if (error != 0) {
 		error = errno;
 		lua_pushnil(L);
 		lua_pushstring(L, strerror(error));
 		lua_pushinteger(L, error);
 		return (3);
 	}
 
 	lua_newtable(L);
 #define	setkv(f) do {			\
 	lua_pushstring(L, name.f);	\
 	lua_setfield(L, -2, #f);	\
 } while (0)
 	setkv(sysname);
 	setkv(nodename);
 	setkv(release);
 	setkv(version);
 	setkv(machine);
 #undef setkv
 
 	return (1);
 }
 
 static int
 lua_dirname(lua_State *L)
 {
 	char *inpath, *outpath;
 
 	enforce_max_args(L, 1);
 
 	inpath = strdup(luaL_checkstring(L, 1));
 	if (inpath == NULL) {
 		lua_pushnil(L);
 		lua_pushstring(L, strerror(ENOMEM));
 		lua_pushinteger(L, ENOMEM);
 		return (3);
 	}
 
 	outpath = dirname(inpath);
 	lua_pushstring(L, outpath);
 	free(inpath);
 	return (1);
 }
 
 static int
 lua_fork(lua_State *L)
 {
 	pid_t pid;
 
 	enforce_max_args(L, 0);
 
 	pid = fork();
 	if (pid < 0) {
 		lua_pushnil(L);
 		lua_pushstring(L, strerror(errno));
 		lua_pushinteger(L, errno);
 		return (3);
 	}
 
 	lua_pushinteger(L, pid);
 	return (1);
 }
 
 static int
 lua_getpid(lua_State *L)
 {
 	enforce_max_args(L, 0);
 
 	lua_pushinteger(L, getpid());
 	return (1);
 }
 
 static int
 lua_pipe(lua_State *L)
 {
 	int error, fd[2];
 
 	enforce_max_args(L, 0);
 
 	error = pipe(fd);
 	if (error != 0) {
 		lua_pushnil(L);
 		lua_pushstring(L, strerror(errno));
 		lua_pushinteger(L, errno);
 		return (1);
 	}
 
 	lua_pushinteger(L, fd[0]);
 	lua_pushinteger(L, fd[1]);
 	return (2);
 }
 
 static int
 lua_read(lua_State *L)
 {
 	char *buf;
 	ssize_t ret;
 	size_t sz;
 	int error, fd;
 
 	enforce_max_args(L, 2);
 	fd = luaL_checkinteger(L, 1);
 	sz = luaL_checkinteger(L, 2);
 
 	if (fd < 0) {
 		error = EBADF;
 		goto err;
 	}
 
 	buf = malloc(sz);
 	if (buf == NULL)
 		goto err;
 
 	/*
 	 * For 0-byte reads, we'll still push the empty string and let the
 	 * caller deal with EOF to match lposix semantics.
 	 */
 	ret = read(fd, buf, sz);
 	if (ret >= 0)
 		lua_pushlstring(L, buf, ret);
 	else if (ret < 0)
 		error = errno; /* Save to avoid clobber by free() */
 
 	free(buf);
 	if (error != 0)
 		goto err;
 
 	/* Just the string pushed. */
 	return (1);
 err:
 	lua_pushnil(L);
 	lua_pushstring(L, strerror(error));
 	lua_pushinteger(L, error);
 	return (3);
 }
 
 static int
 lua_realpath(lua_State *L)
 {
 	const char *inpath;
 	char *outpath;
 
 	enforce_max_args(L, 1);
 	inpath = luaL_checkstring(L, 1);
 
 	outpath = realpath(inpath, NULL);
 	if (outpath == NULL) {
 		lua_pushnil(L);
 		lua_pushstring(L, strerror(errno));
 		lua_pushinteger(L, errno);
 		return (3);
 	}
 
 	lua_pushstring(L, outpath);
 	free(outpath);
 	return (1);
 }
 
 static int
 lua_wait(lua_State *L)
 {
 	pid_t pid;
 	int options, status;
 
 	enforce_max_args(L, 2);
 	pid = luaL_optinteger(L, 1, -1);
 	options = luaL_optinteger(L, 2, 0);
 
 	status = 0;
 	pid = waitpid(pid, &status, options);
 	if (pid < 0) {
 		lua_pushnil(L);
 		lua_pushstring(L, strerror(errno));
 		lua_pushinteger(L, errno);
 		return (3);
 	}
 
 	lua_pushinteger(L, pid);
 	if (pid == 0) {
 		lua_pushliteral(L, "running");
 		return (2);
 	}
 
 	if (WIFCONTINUED(status)) {
 		lua_pushliteral(L, "continued");
 		return (2);
 	} else if(WIFSTOPPED(status)) {
 		lua_pushliteral(L, "stopped");
 		lua_pushinteger(L, WSTOPSIG(status));
 		return (3);
 	} else if (WIFEXITED(status)) {
 		lua_pushliteral(L, "exited");
 		lua_pushinteger(L, WEXITSTATUS(status));
 		return (3);
 	} else if (WIFSIGNALED(status)) {
 		lua_pushliteral(L, "killed");
 		lua_pushinteger(L, WTERMSIG(status));
 		return (3);
 	}
 
 	return (1);
 }
 
 static int
 lua_write(lua_State *L)
 {
 	const char *buf;
 	size_t bufsz, sz;
 	ssize_t ret;
 	off_t offset;
 	int error, fd;
 
 	enforce_max_args(L, 4);
 
 	fd = luaL_checkinteger(L, 1);
 	if (fd < 0) {
 		error = EBADF;
 		goto err;
 	}
 
 	buf = luaL_checkstring(L, 2);
 
 	bufsz = lua_rawlen(L, 2);
 	sz = luaL_optinteger(L, 3, bufsz);
 
 	offset = luaL_optinteger(L, 4, 0);
 
 
 	if ((size_t)offset > bufsz || offset + sz > bufsz) {
 		lua_pushnil(L);
 		lua_pushfstring(L,
 		    "write: invalid access offset %zu, size %zu in a buffer size %zu",
 		    offset, sz, bufsz);
 		lua_pushinteger(L, EINVAL);
 		return (3);
 	}
 
 	ret = write(fd, buf + offset, sz);
 	if (ret < 0) {
 		error = errno;
 		goto err;
 	}
 
 	lua_pushinteger(L, ret);
 	return (1);
 err:
 	lua_pushnil(L);
 	lua_pushstring(L, strerror(error));
 	lua_pushinteger(L, error);
 	return (3);
 }
 
 #define	REG_DEF(n, func)	{ #n, func }
 #define REG_SIMPLE(n)		REG_DEF(n, lua_ ## n)
 static const struct luaL_Reg libgenlib[] = {
 	REG_SIMPLE(basename),
 	REG_SIMPLE(dirname),
 	{ NULL, NULL },
 };
 
 static const struct luaL_Reg stdliblib[] = {
 	REG_SIMPLE(realpath),
 	{ NULL, NULL },
 };
 
 static const struct luaL_Reg fnmatchlib[] = {
 	REG_SIMPLE(fnmatch),
 	{ NULL, NULL },
 };
 
 static const struct luaL_Reg sys_statlib[] = {
 	REG_SIMPLE(chmod),
 	{ NULL, NULL },
 };
 
 static const struct luaL_Reg sys_utsnamelib[] = {
 	REG_SIMPLE(uname),
 	{ NULL, NULL },
 };
 
 static const struct luaL_Reg sys_waitlib[] = {
 	REG_SIMPLE(wait),
 	{NULL, NULL},
 };
 
 static const struct luaL_Reg unistdlib[] = {
 	REG_SIMPLE(_exit),
 	REG_SIMPLE(chown),
 	REG_DEF(close, lua_pclose),
+	REG_SIMPLE(dup2),
 	REG_SIMPLE(fork),
 	REG_SIMPLE(getpid),
 	REG_SIMPLE(pipe),
 	REG_SIMPLE(read),
 	REG_SIMPLE(write),
 	{ NULL, NULL },
 };
 
 #undef REG_SIMPLE
 #undef REG_DEF
 
 int
 luaopen_posix_libgen(lua_State *L)
 {
 	luaL_newlib(L, libgenlib);
 	return (1);
 }
 
 int
 luaopen_posix_stdlib(lua_State *L)
 {
 	luaL_newlib(L, stdliblib);
 	return (1);
 }
 
 int
 luaopen_posix_fnmatch(lua_State *L)
 {
 	luaL_newlib(L, fnmatchlib);
 
 #define	setkv(f) do {			\
 	lua_pushinteger(L, f);		\
 	lua_setfield(L, -2, #f);	\
 } while (0)
 	setkv(FNM_PATHNAME);
 	setkv(FNM_NOESCAPE);
 	setkv(FNM_NOMATCH);
 	setkv(FNM_PERIOD);
 #undef setkv
 
 	return 1;
 }
 
 int
 luaopen_posix_sys_stat(lua_State *L)
 {
 	luaL_newlib(L, sys_statlib);
 	return (1);
 }
 
 int
 luaopen_posix_sys_wait(lua_State *L)
 {
 	luaL_newlib(L, sys_waitlib);
 
 #define	lua_pushflag(L, flag) do {	\
 	lua_pushinteger(L, flag);	\
 	lua_setfield(L, -2, #flag);	\
 } while(0)
 
 	/* Only these two exported by lposix */
 	lua_pushflag(L, WNOHANG);
 	lua_pushflag(L, WUNTRACED);
 
 	lua_pushflag(L, WCONTINUED);
 	lua_pushflag(L, WSTOPPED);
 #ifdef WTRAPPED
 	lua_pushflag(L, WTRAPPED);
 #endif
 	lua_pushflag(L, WEXITED);
 	lua_pushflag(L, WNOWAIT);
 #undef lua_pushflag
 
 	return (1);
 }
 
 int
 luaopen_posix_sys_utsname(lua_State *L)
 {
 	luaL_newlib(L, sys_utsnamelib);
 	return 1;
 }
 
 int
 luaopen_posix_unistd(lua_State *L)
 {
 	luaL_newlib(L, unistdlib);
 	return (1);
 }