diff --git a/CMakeLists.txt b/CMakeLists.txt
index d10aba394..5e28b83a7 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -39,6 +39,19 @@ if(NOT DEFINED C2A_NAME)
   set(C2A_NAME "c2a_oss")
 endif()
 
+## Directory path for ini files
+if(NOT DEFINED INI_FILE_DIR_FROM_EXE)
+  set(INI_FILE_DIR_FROM_EXE ../../data/sample/initialize_files)
+endif()
+
+if(NOT DEFINED EXT_LIB_DIR_FROM_EXE)
+  set(EXT_LIB_DIR_FROM_EXE ../../${EXT_LIB_DIR})
+endif()
+
+if(NOT DEFINED CORE_DIR_FROM_EXE)
+  set(CORE_DIR_FROM_EXE ../../../s2e-core)
+endif()
+
 ## options to use C2A
 if(USE_C2A)
   option(BUILD_64BIT OFF) # force to build with 32bit
diff --git a/common.cmake b/common.cmake
index 03d9a1f11..fcc983a70 100644
--- a/common.cmake
+++ b/common.cmake
@@ -7,6 +7,11 @@ set_target_properties(${PROJECT_NAME} PROPERTIES CXX_EXTENSIONS FALSE)
 target_include_directories(${PROJECT_NAME} PUBLIC ${S2E_DIR}/src)
 target_include_directories(${PROJECT_NAME} PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})
 
+# Directory path setting
+target_compile_definitions(${PROJECT_NAME} PRIVATE "INI_FILE_DIR_FROM_EXE=\"${INI_FILE_DIR_FROM_EXE}\"")
+target_compile_definitions(${PROJECT_NAME} PRIVATE "EXT_LIB_DIR_FROM_EXE=\"${EXT_LIB_DIR_FROM_EXE}\"")
+target_compile_definitions(${PROJECT_NAME} PRIVATE "CORE_DIR_FROM_EXE=\"${CORE_DIR_FROM_EXE}\"")
+
 # Compile option
 if(MSVC)
   target_compile_options(${PROJECT_NAME} PUBLIC "/MP")  # multi process build
diff --git a/data/sample/initialize_files/sample_disturbance.ini b/data/sample/initialize_files/sample_disturbance.ini
index 32da0bd19..7a7dd9690 100644
--- a/data/sample/initialize_files/sample_disturbance.ini
+++ b/data/sample/initialize_files/sample_disturbance.ini
@@ -3,7 +3,7 @@
 calculation = DISABLE
 logging = ENABLE
 degree = 4
-coefficients_file_path = ../../../ExtLibraries/GeoPotential/egm96_to360.ascii
+coefficients_file_path = EXT_LIB_DIR_FROM_EXE/GeoPotential/egm96_to360.ascii
 
 
 [MAGNETIC_DISTURBANCE]
diff --git a/data/sample/initialize_files/sample_gnss.ini b/data/sample/initialize_files/sample_gnss.ini
index 8b978c033..812d9c668 100644
--- a/data/sample/initialize_files/sample_gnss.ini
+++ b/data/sample/initialize_files/sample_gnss.ini
@@ -1,5 +1,5 @@
 [GNSS_SATELLIES]
-directory_path = ../../../ExtLibraries/sp3/
+directory_path = EXT_LIB_DIR_FROM_EXE/sp3/
 calculation = DISABLE
 
 true_position_file_sort = IGS
diff --git a/data/sample/initialize_files/sample_ground_station.ini b/data/sample/initialize_files/sample_ground_station.ini
index e238f6220..ab57e1164 100644
--- a/data/sample/initialize_files/sample_ground_station.ini
+++ b/data/sample/initialize_files/sample_ground_station.ini
@@ -8,5 +8,5 @@ height_m = 3.4
 elevation_limit_angle_deg = 5.0
 
 [COMPONENT_FILES]
-ground_station_antenna_file = ../../data/sample/initialize_files/components/ground_station_antenna.ini
-ground_station_calculator_file = ../../data/sample/initialize_files/components/ground_station_calculator.ini
+ground_station_antenna_file = INI_FILE_DIR_FROM_EXE/components/ground_station_antenna.ini
+ground_station_calculator_file = INI_FILE_DIR_FROM_EXE/components/ground_station_calculator.ini
diff --git a/data/sample/initialize_files/sample_local_environment.ini b/data/sample/initialize_files/sample_local_environment.ini
index e2ca4bd8d..6c6e55a95 100644
--- a/data/sample/initialize_files/sample_local_environment.ini
+++ b/data/sample/initialize_files/sample_local_environment.ini
@@ -1,7 +1,7 @@
 [MAGNETIC_FIELD_ENVIRONMENT]
 calculation = ENABLE
 logging = ENABLE
-coefficient_file = ../../../s2e-core/src/library/external/igrf/igrf13.coef
+coefficient_file = CORE_DIR_FROM_EXE/src/library/external/igrf/igrf13.coef
 magnetic_field_random_walk_standard_deviation_nT = 10.0
 magnetic_field_random_walk_limit_nT = 400.0
 magnetic_field_white_noise_standard_deviation_nT = 50.0
@@ -21,7 +21,7 @@ logging = ENABLE
 // NRLMSISE00: NRLMSISE00 model
 // HARRIS_PRIESTER: Harris-Priester model
 model = STANDARD
-nrlmsise00_table_file = ../../../ExtLibraries/nrlmsise00/table/SpaceWeather-v1.2.txt
+nrlmsise00_table_file = EXT_LIB_DIR_FROM_EXE/nrlmsise00/table/SpaceWeather-v1.2.txt
 // Whether using user-defined f10.7 and ap value
 // Ref of f10.7: https://www.swpc.noaa.gov/phenomena/f107-cm-radio-emissions
 // Ref of ap: http://wdc.kugi.kyoto-u.ac.jp/kp/kpexp-j.html
diff --git a/data/sample/initialize_files/sample_satellite.ini b/data/sample/initialize_files/sample_satellite.ini
index 471ce501f..f5f3dc3cc 100644
--- a/data/sample/initialize_files/sample_satellite.ini
+++ b/data/sample/initialize_files/sample_satellite.ini
@@ -126,22 +126,22 @@ error_tolerance = 0.0001
 calculation = DISABLE
 debug = DISABLE
 solar_calc_setting = DISABLE
-thermal_file_directory = ../../data/sample/initialize_files/thermal_csv_files/
+thermal_file_directory = INI_FILE_DIR_FROM_EXE/thermal_csv_files/
 
 [SETTING_FILES]
-local_environment_file = ../../data/sample/initialize_files/sample_local_environment.ini
-disturbance_file  = ../../data/sample/initialize_files/sample_disturbance.ini
-structure_file = ../../data/sample/initialize_files/sample_structure.ini
+local_environment_file = INI_FILE_DIR_FROM_EXE/sample_local_environment.ini
+disturbance_file  = INI_FILE_DIR_FROM_EXE/sample_disturbance.ini
+structure_file = INI_FILE_DIR_FROM_EXE/sample_structure.ini
 
 [COMPONENT_FILES]
-gyro_file = ../../data/sample/initialize_files/components/gyro_sensor.ini
-magnetometer_file = ../../data/sample/initialize_files/components/magnetometer.ini
-stt_file = ../../data/sample/initialize_files/components/star_sensor.ini
-ss_file = ../../data/sample/initialize_files/components/sun_sensor.ini
-gnss_file = ../../data/sample/initialize_files/components/gnss_receiver.ini
-magetorquer_file = ../../data/sample/initialize_files/components/magnetorquer.ini
-rw_file = ../../data/sample/initialize_files/components/reaction_wheel.ini
-thruster_file = ../../data/sample/initialize_files/components/thruster.ini
-force_generator_file = ../../data/sample/initialize_files/components/force_generator.ini
-torque_generator_file = ../../data/sample/initialize_files/components/torque_generator.ini
-antenna_file = ../../data/sample/initialize_files/components/spacecraft_antenna.ini
+gyro_file = INI_FILE_DIR_FROM_EXE/components/gyro_sensor.ini
+magnetometer_file = INI_FILE_DIR_FROM_EXE/components/magnetometer.ini
+stt_file = INI_FILE_DIR_FROM_EXE/components/star_sensor.ini
+ss_file = INI_FILE_DIR_FROM_EXE/components/sun_sensor.ini
+gnss_file = INI_FILE_DIR_FROM_EXE/components/gnss_receiver.ini
+magetorquer_file = INI_FILE_DIR_FROM_EXE/components/magnetorquer.ini
+rw_file = INI_FILE_DIR_FROM_EXE/components/reaction_wheel.ini
+thruster_file = INI_FILE_DIR_FROM_EXE/components/thruster.ini
+force_generator_file = INI_FILE_DIR_FROM_EXE/components/force_generator.ini
+torque_generator_file = INI_FILE_DIR_FROM_EXE/components/torque_generator.ini
+antenna_file = INI_FILE_DIR_FROM_EXE/components/spacecraft_antenna.ini
diff --git a/data/sample/initialize_files/sample_simulation_base.ini b/data/sample/initialize_files/sample_simulation_base.ini
index c9a814ef1..5f27bbc5a 100644
--- a/data/sample/initialize_files/sample_simulation_base.ini
+++ b/data/sample/initialize_files/sample_simulation_base.ini
@@ -105,15 +105,15 @@ selected_body_name(10) = PLUTO
 
 [CSPICE_KERNELS]
 // CSPICE Kernel files definition
-tls  = ../../../ExtLibraries/cspice/generic_kernels/lsk/naif0010.tls
-tpc1 = ../../../ExtLibraries/cspice/generic_kernels/pck/de-403-masses.tpc
-tpc2 = ../../../ExtLibraries/cspice/generic_kernels/pck/gm_de431.tpc
-tpc3 = ../../../ExtLibraries/cspice/generic_kernels/pck/pck00010.tpc
-bsp  = ../../../ExtLibraries/cspice/generic_kernels/spk/planets/de430.bsp
+tls  = EXT_LIB_DIR_FROM_EXE/cspice/generic_kernels/lsk/naif0010.tls
+tpc1 = EXT_LIB_DIR_FROM_EXE/cspice/generic_kernels/pck/de-403-masses.tpc
+tpc2 = EXT_LIB_DIR_FROM_EXE/cspice/generic_kernels/pck/gm_de431.tpc
+tpc3 = EXT_LIB_DIR_FROM_EXE/cspice/generic_kernels/pck/pck00010.tpc
+bsp  = EXT_LIB_DIR_FROM_EXE/cspice/generic_kernels/spk/planets/de430.bsp
 
 
 [HIPPARCOS_CATALOGUE]
-catalogue_file_path = ../../../ExtLibraries/HipparcosCatalogue/hip_main.csv
+catalogue_file_path = EXT_LIB_DIR_FROM_EXE/HipparcosCatalogue/hip_main.csv
 max_magnitude = 3.0	// Max magnitude to read from Hip catalog
 calculation = DISABLE
 logging = DISABLE
@@ -134,7 +134,7 @@ save_initialize_files = ENABLE
 // If you want to add a ground station, create the corresponding ground_station.ini, and specify it as ground_station_file(1), ground_station_file(2), ect.
 number_of_simulated_spacecraft = 1
 number_of_simulated_ground_station = 1
-spacecraft_file(0)      = ../../data/sample/initialize_files/sample_satellite.ini
-ground_station_file(0)  = ../../data/sample/initialize_files/sample_ground_station.ini
-gnss_file               = ../../data/sample/initialize_files/sample_gnss.ini
+spacecraft_file(0)      = INI_FILE_DIR_FROM_EXE/sample_satellite.ini
+ground_station_file(0)  = INI_FILE_DIR_FROM_EXE/sample_ground_station.ini
+gnss_file               = INI_FILE_DIR_FROM_EXE/sample_gnss.ini
 log_file_save_directory = ../../data/sample/logs/
diff --git a/src/library/initialize/initialize_file_access.cpp b/src/library/initialize/initialize_file_access.cpp
index 73db33cc9..407a1aade 100644
--- a/src/library/initialize/initialize_file_access.cpp
+++ b/src/library/initialize/initialize_file_access.cpp
@@ -10,6 +10,7 @@
 #include <algorithm>
 #include <cstring>
 #include <limits>
+#include <regex>
 
 #include "../utilities/macros.hpp"
 
@@ -120,14 +121,26 @@ void IniAccess::ReadChar(const char* section_name, const char* key_name, const i
 }
 
 std::string IniAccess::ReadString(const char* section_name, const char* key_name) {
+  std::string value;
 #ifdef WIN32
   char temp[kMaxCharLength];
   ReadChar(section_name, key_name, kMaxCharLength, temp);
-  return std::string(temp);
+  value = std::string(temp);
 #else
-  std::string value = ini_reader_.GetString(section_name, key_name, "NULL");
-  return value;
+  value = ini_reader_.GetString(section_name, key_name, "NULL");
 #endif
+  // Special characters
+  // INI_FILE_DIR
+  std::string ini_path = INI_FILE_DIR_FROM_EXE;
+  value = std::regex_replace(value, std::regex("INI_FILE_DIR_FROM_EXE"), ini_path);
+  // EXT_LIB_DIR
+  std::string ext_lib_path = EXT_LIB_DIR_FROM_EXE;
+  value = std::regex_replace(value, std::regex("EXT_LIB_DIR_FROM_EXE"), ext_lib_path);
+  // CORE_DIR
+  std::string s2e_core_path = CORE_DIR_FROM_EXE;
+  value = std::regex_replace(value, std::regex("CORE_DIR_FROM_EXE"), s2e_core_path);
+
+  return value;
 }
 
 bool IniAccess::ReadEnable(const char* section_name, const char* key_name) {
@@ -139,16 +152,16 @@ bool IniAccess::ReadEnable(const char* section_name, const char* key_name) {
 
 std::vector<std::string> IniAccess::ReadStrVector(const char* section_name, const char* key_name) {
   std::vector<std::string> data;
-  char temp[kMaxCharLength];
+  std::string temp;
   unsigned int i = 0;
   while (true) {
     std::stringstream c_name;
     c_name << key_name << "(" << i << ")";
-    ReadChar(section_name, c_name.str().c_str(), kMaxCharLength, temp);
+    temp = ReadString(section_name, c_name.str().c_str());
 #ifdef WIN32
-    if (temp[0] == NULL) {
+    if (temp.c_str()[0] == NULL) {
 #else
-    if (!strcmp(temp, "NULL")) {
+    if (!strcmp(temp.c_str(), "NULL")) {
 #endif
       break;
     } else {
diff --git a/src/s2e.cpp b/src/s2e.cpp
index 63001e86f..ed446ee20 100644
--- a/src/s2e.cpp
+++ b/src/s2e.cpp
@@ -47,7 +47,8 @@ int main(int argc, char *argv[])
   start = system_clock::now();
 
   std::string data_path = "../../data/";
-  std::string ini_file = "../../data/sample/initialize_files/sample_simulation_base.ini";
+  std::string ini_path = INI_FILE_DIR_FROM_EXE;
+  std::string ini_file = ini_path + "/sample_simulation_base.ini";
 
   // Parsing arguments:  SatAttSim <data_path> [ini_file]
   if (argc == 0) {