diff --git a/security-tool.sh b/security-tool.sh
index c6bc4e7003aa0149c5db584202432f0a88c75a83..b6914dd4186904123b4d64ea308da3d0dd467078 100644
--- a/security-tool.sh
+++ b/security-tool.sh
@@ -643,8 +643,12 @@ function fn_handle_umask()
 
     if [ "$target" == "user" ]
     then
-        echo "umask $value" >> "$ROOTFS/etc/bashrc"
-        echo "umask $value" >> "$ROOTFS/etc/csh.cshrc"
+        if ! grep -q "^umask $value" $ROOTFS/etc/bashrc;then
+            echo "umask $value" >> "$ROOTFS/etc/bashrc"
+        fi
+        if ! grep -q "^umask $value" $ROOTFS/etc/csh.cshrc;then 
+            echo "umask $value" >> "$ROOTFS/etc/csh.cshrc"
+        fi
         for file in $(find "$ROOTFS/etc/profile.d/" -type f)
         do
            echo '' >> $file # 防止配置文件末尾没有换行符的情况