diff --git a/src/cleardns.c b/src/cleardns.c
index e1f4f0e..3ad366a 100644
--- a/src/cleardns.c
+++ b/src/cleardns.c
@@ -115,12 +115,8 @@ void cleardns() { // cleardns service
 }
 
 int main(int argc, char *argv[]) {
-//    init(argc, argv);
-//    log_info("ClearDNS server start (%s)", VERSION);
-//    cleardns();
-
-    char *test = string_load("`%s` -> %d", "test", 2333);
-    printf("%s\n", test);
-
+    init(argc, argv);
+    log_info("ClearDNS server start (%s)", VERSION);
+    cleardns();
     return 0;
 }
diff --git a/src/common/json.c b/src/common/json.c
index 7d308c2..95f33e7 100644
--- a/src/common/json.c
+++ b/src/common/json.c
@@ -1,4 +1,3 @@
-#include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include "cJSON.h"
@@ -27,8 +26,7 @@ char* to_json(const char *file) { // convert JSON / TOML / YAML to json format (
     flag[8] = '\0';
 
     char *output_file = string_join("/tmp/to-json-", flag);
-    char *to_json_cmd = (char *)malloc(strlen(file) + strlen(output_file) + 11);
-    sprintf(to_json_cmd, "toJSON %s > %s", file, output_file);
+    char *to_json_cmd = string_load("toJSON %s > %s", file, output_file);
     int to_json_ret = run_command(to_json_cmd);
     free(to_json_cmd);
 
diff --git a/src/common/structure.c b/src/common/structure.c
index a8b0e8a..2698e86 100644
--- a/src/common/structure.c
+++ b/src/common/structure.c
@@ -92,7 +92,7 @@ char* uint32_list_dump(uint32_t **uint32_list) { // [1, 2, 3, ...]
     strcpy(string_ret, "[");
     for (uint32_t **number = uint32_list; *number != NULL; ++number) {
         sprintf(uint32_str, "%u", **number);
-        string_ret = (char*)realloc(string_ret, strlen(string_ret) + 15);
+        string_ret = (char *)realloc(string_ret, strlen(string_ret) + 15);
         string_ret = strcat(strcat(string_ret, uint32_str), ", ");
     }
     string_ret[strlen(string_ret) - 2] = '\0';
diff --git a/src/common/system.c b/src/common/system.c
index f59318c..476d579 100644
--- a/src/common/system.c
+++ b/src/common/system.c
@@ -4,6 +4,7 @@
 #include <unistd.h>
 #include <sys/stat.h>
 #include "logger.h"
+#include "sundry.h"
 #include "system.h"
 #include "constant.h"
 
@@ -65,8 +66,7 @@ void save_file(const char *file, const char *content) { // save content into fil
 }
 
 void file_append(const char *base_file, const char *append_file) { // append_file >> base_file
-    char *append_cmd = (char *)malloc(strlen(base_file) + strlen(append_file) + 9);
-    sprintf(append_cmd, "cat %s >> %s", append_file, base_file);
+    char *append_cmd = string_load("cat %s >> %s", append_file, base_file);
     run_command(append_cmd);
     free(append_cmd);
 }
@@ -108,8 +108,7 @@ void save_string_list(const char *file, char **string_list) { // save string lis
 
 void download_file(const char *file, const char *url) { // download file
     log_debug("Download file `%s` -> %s", file, url);
-    char *download_cmd = (char *)malloc(strlen(file) + strlen(url) + 15);
-    sprintf(download_cmd, "wget -T 8 -O %s %s", file, url);
+    char *download_cmd = string_load("wget -T 8 -O %s %s", file, url);
     if (run_command(download_cmd)) {
         log_warn("File `%s` download failed", url);
     }
diff --git a/src/utils/assets.c b/src/utils/assets.c
index 6b9bb89..9f31f42 100644
--- a/src/utils/assets.c
+++ b/src/utils/assets.c
@@ -1,4 +1,3 @@
-#include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <signal.h>
@@ -81,8 +80,7 @@ void extract(const char *file) { // extract one asset file from `.tar.xz` file
     }
     free(output_file);
 
-    char *extract_cmd = (char *)malloc(strlen(ASSETS_PKG) + strlen(file) + strlen(ASSETS_DIR) + 13);
-    sprintf(extract_cmd, "tar xf %s %s -C %s", ASSETS_PKG, file, ASSETS_DIR);
+    char *extract_cmd = string_load("tar xf %s %s -C %s", ASSETS_PKG, file, ASSETS_DIR);
     if (run_command(extract_cmd)) {
         log_warn("Extract asset `%s` failed", file);
     } else {