feat(add): create add script

src/add-sshkey.cc

@@ -0,0 +1,53 @@
+#include <iostream>
+#include <fstream>
+
+int append_key(std::string &key, std::fstream &file)
+{
+    std::string tmp;
+
+    while (getline(file, tmp))
+    {
+        if (tmp == key)
+            return 1;
+    }
+
+    file << "\n" << key;
+
+    if (file.bad())
+        return 2;
+
+    return 0;
+}
+
+int main(int argc, char *argv[])
+{
+    if (argc != 2)
+    {
+        std::cerr << "[!!] This program needs one (1) argument to work, exiting."
+                  << std::endl;
+        return 1;
+    }
+
+    std::string key(argv[1]);
+
+    std::fstream file("~/.ssh/authorized_keys");
+
+    int res = append_key(key, file);
+    file.close();
+
+    if (res == 1)
+    {
+        std::cerr << "[!!] The key has already been added, exiting."i
+                  << std::endl;
+    }
+    else if (res == 2)
+    {
+        std::cerr << "[!!] Error while writing key, exiting." << std::endl;
+    }
+    else
+    {
+        std::cerr << "[++] Key has been added." << std::endl;
+    }
+
+    return 0;
+}