diff --git a/default.config b/default.config
index 50a2a53..27e2a1e 100644
--- a/default.config
+++ b/default.config
@@ -1,5 +1,5 @@
 #!/bin/bash
-CBUILD_VERSION=3
+CBUILD_VERSION=4
 CONFIG_VERSION=1
 
 PROJECT="NULL"
@@ -25,6 +25,7 @@ case $TASK in
         C_ARGS="-O2"
         CPP_ARGS="$C_ARGS"
         LINKER_ARGS=""
+        LINK_LIBS=""
         TASK_SCRIPT=cbuild/default_tasks/build_exec.sh
         PRE_TASK_SCRIPT=
         POST_TASK_SCRIPT=
@@ -33,6 +34,7 @@ case $TASK in
         C_ARGS="-O0 -g"
         CPP_ARGS="$C_ARGS"
         LINKER_ARGS=""
+        LINK_LIBS=""
         TASK_SCRIPT=cbuild/default_tasks/build_exec.sh
         PRE_TASK_SCRIPT=
         POST_TASK_SCRIPT=
@@ -40,6 +42,7 @@ case $TASK in
     build_shared_lib)
         C_ARGS="-O2 -fpic -flto -shared"
         CPP_ARGS="$C_ARGS"
+        LINK_LIBS=""
         LINKER_ARGS="-Wl,-soname,$SHARED_LIB_FILE"
         TASK_SCRIPT=cbuild/default_tasks/build_shared_lib.sh
         PRE_TASK_SCRIPT=
@@ -48,6 +51,7 @@ case $TASK in
     build_shared_lib_dbg)
         C_ARGS="-O0 -g -fpic -shared"
         CPP_ARGS="$C_ARGS"
+        LINK_LIBS=""
         LINKER_ARGS="-Wl,-soname,$SHARED_LIB_FILE"
         TASK_SCRIPT=cbuild/default_tasks/build_shared_lib.sh
         PRE_TASK_SCRIPT=
@@ -55,14 +59,14 @@ case $TASK in
         ;;
     build_static_lib)
         C_ARGS="-O2 -fpic"
-        CPP_ARGS="$C_ARGS" 
+        CPP_ARGS="$C_ARGS"
         TASK_SCRIPT=cbuild/default_tasks/build_static_lib.sh
         PRE_TASK_SCRIPT=
         POST_TASK_SCRIPT=
         ;;
     build_static_lib_dbg)
         C_ARGS="-O0 -g"
-        CPP_ARGS="$C_ARGS" 
+        CPP_ARGS="$C_ARGS"
         TASK_SCRIPT=cbuild/default_tasks/build_static_lib.sh
         PRE_TASK_SCRIPT=
         POST_TASK_SCRIPT=
@@ -75,3 +79,14 @@ case $TASK in
         TASK_SCRIPT=cbuild/default_tasks/valgrind.sh
         ;;
 esac
+
+case $OS in
+    WINDOWS)
+        ;;
+    LINUX)
+        ;;
+    *)
+        printf "${RED}operating system $OS has no configuration variants\n"
+        exit 1
+        ;;
+esac
diff --git a/detect_os.sh b/detect_os.sh
new file mode 100644
index 0000000..d08d8c5
--- /dev/null
+++ b/detect_os.sh
@@ -0,0 +1,27 @@
+#!/bin/bash
+
+source cbuild/colors.sh
+
+uname_rezult=$(uname -o);
+printf "${GRAY}uname rezult: '$uname_rezult'\n"
+
+case $uname_rezult in
+    Msys | Cygwin | "MS/Windows")
+        OS=WINDOWS
+        ;;
+    GNU/Linux)
+        OS=LINUX
+        ;;
+    FreeBSD)
+        OS=FREEBSD
+        ;;
+    Darwin)
+        OS=MACOS
+        ;;
+    *)
+        printf "${RED}unknown operating system: $uname_rezult\n"
+        exit 1
+        ;;
+esac
+
+printf "${GREEN}detected OS: $OS\n"
diff --git a/functions.sh b/functions.sh
index 118d6cd..cdaa299 100755
--- a/functions.sh
+++ b/functions.sh
@@ -60,7 +60,9 @@ function link {
     local objects="$(find $OBJDIR -name '*.o')
 $(find $OBJDIR -name '*.a')"
     printf "${BLUE}objects: ${GRAY}$objects\n"
-    if $CMP_CPP $args -o $outfile $(echo $objects | tr '\n' ' ')
+    local command="$CMP_CPP $args $(echo $objects | tr '\n' ' ') $LINK_LIBS -o $outfile"
+    printf "$command"
+    if $command
     then 
         printf "${GREEN}file $CYAN$outfile ${GREEN}created\n${GRAY}"
     else
diff --git a/init.sh b/init.sh
index 0bc8b08..3c121ea 100755
--- a/init.sh
+++ b/init.sh
@@ -1,6 +1,7 @@
 #!/bin/bash
 source cbuild/colors.sh
 source cbuild/functions.sh
+source cbuild/detect_os.sh
 # exit on errors
 set -eo pipefail