diff --git a/builtin/apply.c b/builtin/apply.c
index deb1364fa8..d61ac65dab 100644
--- a/builtin/apply.c
+++ b/builtin/apply.c
@@ -4464,16 +4464,6 @@ static int option_parse_p(const struct option *opt,
 	return 0;
 }
 
-static int option_parse_z(const struct option *opt,
-			  const char *arg, int unset)
-{
-	if (unset)
-		line_termination = '\n';
-	else
-		line_termination = 0;
-	return 0;
-}
-
 static int option_parse_space_change(const struct option *opt,
 			  const char *arg, int unset)
 {
@@ -4546,9 +4536,9 @@ int cmd_apply(int argc, const char **argv, const char *prefix_)
 			 N_( "attempt three-way merge if a patch does not apply")),
 		OPT_FILENAME(0, "build-fake-ancestor", &fake_ancestor,
 			N_("build a temporary index based on embedded index information")),
-		{ OPTION_CALLBACK, 'z', NULL, NULL, NULL,
-			N_("paths are separated with NUL character"),
-			PARSE_OPT_NOARG, option_parse_z },
+		/* Think twice before adding "--nul" synonym to this */
+		OPT_SET_INT('z', NULL, &line_termination,
+			N_("paths are separated with NUL character"), '\0'),
 		OPT_INTEGER('C', NULL, &p_context,
 				N_("ensure at least <n> lines of context match")),
 		{ OPTION_CALLBACK, 0, "whitespace", &whitespace_option, N_("action"),
diff --git a/builtin/check-attr.c b/builtin/check-attr.c
index 087325ef69..53a5a18c16 100644
--- a/builtin/check-attr.c
+++ b/builtin/check-attr.c
@@ -72,24 +72,23 @@ static void check_attr(const char *prefix, int cnt,
 static void check_attr_stdin_paths(const char *prefix, int cnt,
 	struct git_attr_check *check)
 {
-	struct strbuf buf, nbuf;
+	struct strbuf buf = STRBUF_INIT;
+	struct strbuf unquoted = STRBUF_INIT;
 	strbuf_getline_fn getline_fn;
 
 	getline_fn = nul_term_line ? strbuf_getline_nul : strbuf_getline_lf;
-	strbuf_init(&buf, 0);
-	strbuf_init(&nbuf, 0);
 	while (getline_fn(&buf, stdin) != EOF) {
 		if (!nul_term_line && buf.buf[0] == '"') {
-			strbuf_reset(&nbuf);
-			if (unquote_c_style(&nbuf, buf.buf, NULL))
+			strbuf_reset(&unquoted);
+			if (unquote_c_style(&unquoted, buf.buf, NULL))
 				die("line is badly quoted");
-			strbuf_swap(&buf, &nbuf);
+			strbuf_swap(&buf, &unquoted);
 		}
 		check_attr(prefix, cnt, check, buf.buf);
 		maybe_flush_or_die(stdout, "attribute to stdout");
 	}
 	strbuf_release(&buf);
-	strbuf_release(&nbuf);
+	strbuf_release(&unquoted);
 }
 
 static NORETURN void error_with_usage(const char *msg)
diff --git a/builtin/check-ignore.c b/builtin/check-ignore.c
index 4f0b09e2db..1d73d3ca3d 100644
--- a/builtin/check-ignore.c
+++ b/builtin/check-ignore.c
@@ -115,20 +115,19 @@ static int check_ignore(struct dir_struct *dir,
 
 static int check_ignore_stdin_paths(struct dir_struct *dir, const char *prefix)
 {
-	struct strbuf buf, nbuf;
+	struct strbuf buf = STRBUF_INIT;
+	struct strbuf unquoted = STRBUF_INIT;
 	char *pathspec[2] = { NULL, NULL };
 	strbuf_getline_fn getline_fn;
 	int num_ignored = 0;
 
 	getline_fn = nul_term_line ? strbuf_getline_nul : strbuf_getline_lf;
-	strbuf_init(&buf, 0);
-	strbuf_init(&nbuf, 0);
 	while (getline_fn(&buf, stdin) != EOF) {
 		if (!nul_term_line && buf.buf[0] == '"') {
-			strbuf_reset(&nbuf);
-			if (unquote_c_style(&nbuf, buf.buf, NULL))
+			strbuf_reset(&unquoted);
+			if (unquote_c_style(&unquoted, buf.buf, NULL))
 				die("line is badly quoted");
-			strbuf_swap(&buf, &nbuf);
+			strbuf_swap(&buf, &unquoted);
 		}
 		pathspec[0] = buf.buf;
 		num_ignored += check_ignore(dir, prefix,
@@ -136,7 +135,7 @@ static int check_ignore_stdin_paths(struct dir_struct *dir, const char *prefix)
 		maybe_flush_or_die(stdout, "check-ignore to stdout");
 	}
 	strbuf_release(&buf);
-	strbuf_release(&nbuf);
+	strbuf_release(&unquoted);
 	return num_ignored;
 }
 
diff --git a/builtin/checkout-index.c b/builtin/checkout-index.c
index ed888a5b9e..92c69672e9 100644
--- a/builtin/checkout-index.c
+++ b/builtin/checkout-index.c
@@ -130,33 +130,6 @@ static const char * const builtin_checkout_index_usage[] = {
 
 static struct lock_file lock_file;
 
-static int option_parse_u(const struct option *opt,
-			      const char *arg, int unset)
-{
-	int *newfd = opt->value;
-
-	state.refresh_cache = 1;
-	state.istate = &the_index;
-	if (*newfd < 0)
-		*newfd = hold_locked_index(&lock_file, 1);
-	return 0;
-}
-
-static int option_parse_z(const struct option *opt,
-			  const char *arg, int unset)
-{
-	nul_term_line = !unset;
-	return 0;
-}
-
-static int option_parse_prefix(const struct option *opt,
-			       const char *arg, int unset)
-{
-	state.base_dir = arg;
-	state.base_dir_len = strlen(arg);
-	return 0;
-}
-
 static int option_parse_stage(const struct option *opt,
 			      const char *arg, int unset)
 {
@@ -168,7 +141,7 @@ static int option_parse_stage(const struct option *opt,
 		if ('1' <= ch && ch <= '3')
 			checkout_stage = arg[0] - '0';
 		else
-			die("stage should be between 1 and 3 or all");
+			die(_("stage should be between 1 and 3 or all"));
 	}
 	return 0;
 }
@@ -181,6 +154,7 @@ int cmd_checkout_index(int argc, const char **argv, const char *prefix)
 	int read_from_stdin = 0;
 	int prefix_length;
 	int force = 0, quiet = 0, not_new = 0;
+	int index_opt = 0;
 	struct option builtin_checkout_index_options[] = {
 		OPT_BOOL('a', "all", &all,
 			N_("check out all files in the index")),
@@ -189,22 +163,19 @@ int cmd_checkout_index(int argc, const char **argv, const char *prefix)
 			N_("no warning for existing files and files not in index")),
 		OPT_BOOL('n', "no-create", &not_new,
 			N_("don't checkout new files")),
-		{ OPTION_CALLBACK, 'u', "index", &newfd, NULL,
-			N_("update stat information in the index file"),
-			PARSE_OPT_NOARG, option_parse_u },
-		{ OPTION_CALLBACK, 'z', NULL, NULL, NULL,
-			N_("paths are separated with NUL character"),
-			PARSE_OPT_NOARG, option_parse_z },
+		OPT_BOOL('u', "index", &index_opt,
+			 N_("update stat information in the index file")),
+		OPT_BOOL('z', NULL, &nul_term_line,
+			N_("paths are separated with NUL character")),
 		OPT_BOOL(0, "stdin", &read_from_stdin,
 			N_("read list of paths from the standard input")),
 		OPT_BOOL(0, "temp", &to_tempfile,
 			N_("write the content to temporary files")),
-		OPT_CALLBACK(0, "prefix", NULL, N_("string"),
-			N_("when creating files, prepend <string>"),
-			option_parse_prefix),
-		OPT_CALLBACK(0, "stage", NULL, NULL,
+		OPT_STRING(0, "prefix", &state.base_dir, N_("string"),
+			N_("when creating files, prepend <string>")),
+		{ OPTION_CALLBACK, 0, "stage", NULL, "1-3|all",
 			N_("copy out the files from named stage"),
-			option_parse_stage),
+			PARSE_OPT_NONEG, option_parse_stage },
 		OPT_END()
 	};
 
@@ -212,7 +183,6 @@ int cmd_checkout_index(int argc, const char **argv, const char *prefix)
 		usage_with_options(builtin_checkout_index_usage,
 				   builtin_checkout_index_options);
 	git_config(git_default_config, NULL);
-	state.base_dir = "";
 	prefix_length = prefix ? strlen(prefix) : 0;
 
 	if (read_cache() < 0) {
@@ -225,15 +195,17 @@ int cmd_checkout_index(int argc, const char **argv, const char *prefix)
 	state.quiet = quiet;
 	state.not_new = not_new;
 
-	if (state.base_dir_len || to_tempfile) {
-		/* when --prefix is specified we do not
-		 * want to update cache.
-		 */
-		if (state.refresh_cache) {
-			rollback_lock_file(&lock_file);
-			newfd = -1;
-		}
-		state.refresh_cache = 0;
+	if (!state.base_dir)
+		state.base_dir = "";
+	state.base_dir_len = strlen(state.base_dir);
+
+	/*
+	 * when --prefix is specified we do not want to update cache.
+	 */
+	if (index_opt && !state.base_dir_len && !to_tempfile) {
+		state.refresh_cache = 1;
+		state.istate = &the_index;
+		newfd = hold_locked_index(&lock_file, 1);
 	}
 
 	/* Check out named files first */
@@ -251,7 +223,8 @@ int cmd_checkout_index(int argc, const char **argv, const char *prefix)
 	}
 
 	if (read_from_stdin) {
-		struct strbuf buf = STRBUF_INIT, nbuf = STRBUF_INIT;
+		struct strbuf buf = STRBUF_INIT;
+		struct strbuf unquoted = STRBUF_INIT;
 		strbuf_getline_fn getline_fn;
 
 		if (all)
@@ -261,16 +234,16 @@ int cmd_checkout_index(int argc, const char **argv, const char *prefix)
 		while (getline_fn(&buf, stdin) != EOF) {
 			char *p;
 			if (!nul_term_line && buf.buf[0] == '"') {
-				strbuf_reset(&nbuf);
-				if (unquote_c_style(&nbuf, buf.buf, NULL))
+				strbuf_reset(&unquoted);
+				if (unquote_c_style(&unquoted, buf.buf, NULL))
 					die("line is badly quoted");
-				strbuf_swap(&buf, &nbuf);
+				strbuf_swap(&buf, &unquoted);
 			}
 			p = prefix_path(prefix, prefix_length, buf.buf);
 			checkout_file(p, prefix);
 			free(p);
 		}
-		strbuf_release(&nbuf);
+		strbuf_release(&unquoted);
 		strbuf_release(&buf);
 	}
 
diff --git a/builtin/hash-object.c b/builtin/hash-object.c
index ff20395c69..f7d3567dd0 100644
--- a/builtin/hash-object.c
+++ b/builtin/hash-object.c
@@ -58,20 +58,21 @@ static void hash_object(const char *path, const char *type, const char *vpath,
 static void hash_stdin_paths(const char *type, int no_filters, unsigned flags,
 			     int literally)
 {
-	struct strbuf buf = STRBUF_INIT, nbuf = STRBUF_INIT;
+	struct strbuf buf = STRBUF_INIT;
+	struct strbuf unquoted = STRBUF_INIT;
 
 	while (strbuf_getline(&buf, stdin) != EOF) {
 		if (buf.buf[0] == '"') {
-			strbuf_reset(&nbuf);
-			if (unquote_c_style(&nbuf, buf.buf, NULL))
+			strbuf_reset(&unquoted);
+			if (unquote_c_style(&unquoted, buf.buf, NULL))
 				die("line is badly quoted");
-			strbuf_swap(&buf, &nbuf);
+			strbuf_swap(&buf, &unquoted);
 		}
 		hash_object(buf.buf, type, no_filters ? NULL : buf.buf, flags,
 			    literally);
 	}
 	strbuf_release(&buf);
-	strbuf_release(&nbuf);
+	strbuf_release(&unquoted);
 }
 
 int cmd_hash_object(int argc, const char **argv, const char *prefix)
diff --git a/builtin/ls-files.c b/builtin/ls-files.c
index dedf02dc70..f02e3d23bb 100644
--- a/builtin/ls-files.c
+++ b/builtin/ls-files.c
@@ -379,14 +379,6 @@ static const char * const ls_files_usage[] = {
 	NULL
 };
 
-static int option_parse_z(const struct option *opt,
-			  const char *arg, int unset)
-{
-	line_terminator = unset ? '\n' : '\0';
-
-	return 0;
-}
-
 static int option_parse_exclude(const struct option *opt,
 				const char *arg, int unset)
 {
@@ -428,9 +420,9 @@ int cmd_ls_files(int argc, const char **argv, const char *cmd_prefix)
 	struct exclude_list *el;
 	struct string_list exclude_list = STRING_LIST_INIT_NODUP;
 	struct option builtin_ls_files_options[] = {
-		{ OPTION_CALLBACK, 'z', NULL, NULL, NULL,
-			N_("paths are separated with NUL character"),
-			PARSE_OPT_NOARG, option_parse_z },
+		/* Think twice before adding "--nul" synonym to this */
+		OPT_SET_INT('z', NULL, &line_terminator,
+			N_("paths are separated with NUL character"), '\0'),
 		OPT_BOOL('t', NULL, &show_tag,
 			N_("identify the file status with tags")),
 		OPT_BOOL('v', NULL, &show_valid_bit,
diff --git a/builtin/update-index.c b/builtin/update-index.c
index dbc23a46b1..1c94ca59bf 100644
--- a/builtin/update-index.c
+++ b/builtin/update-index.c
@@ -1086,16 +1086,17 @@ int cmd_update_index(int argc, const char **argv, const char *prefix)
 	}
 
 	if (read_from_stdin) {
-		struct strbuf buf = STRBUF_INIT, nbuf = STRBUF_INIT;
+		struct strbuf buf = STRBUF_INIT;
+		struct strbuf unquoted = STRBUF_INIT;
 
 		setup_work_tree();
 		while (getline_fn(&buf, stdin) != EOF) {
 			char *p;
 			if (!nul_term_line && buf.buf[0] == '"') {
-				strbuf_reset(&nbuf);
-				if (unquote_c_style(&nbuf, buf.buf, NULL))
+				strbuf_reset(&unquoted);
+				if (unquote_c_style(&unquoted, buf.buf, NULL))
 					die("line is badly quoted");
-				strbuf_swap(&buf, &nbuf);
+				strbuf_swap(&buf, &unquoted);
 			}
 			p = prefix_path(prefix, prefix_length, buf.buf);
 			update_one(p);
@@ -1103,7 +1104,7 @@ int cmd_update_index(int argc, const char **argv, const char *prefix)
 				chmod_path(set_executable_bit, p);
 			free(p);
 		}
-		strbuf_release(&nbuf);
+		strbuf_release(&unquoted);
 		strbuf_release(&buf);
 	}