How can i set my environment variable in c++ without passing command line argument

Question

I am using execv to set environment variable by passing command line argument. how to set environment variable without passing command line argument.

std::vector<char*> arg;
arg.push_back("export MONGODB_HOSTNAME=" + mongodb_host + ";");
arg.push_back("export MONGODB_USERNAME=" + mongo_username + ";");
arg.push_back("export MONGODB_PASSWORD=" + mongo_passowrd + ";"); 
arg.push_back("NULL");
execv("/usr/bin/ssh", &arg.front());

Answer 1

Depending on your threat model, perhaps you can get away with setting environment variables via /usr/bin/env ?

This would look something like the following:

std::vector<std::string> strArgs = {
    "ssh",
    "remote-server",
    "env",
    "MONGODB_USERNAME=" + mongo_username,
    "MONGODB_PASSWORD=" + mongo_password,
    "mongo"
};

// Convert std::vector<std::string> into char**
std::vector<char*> cArgs;
for (auto& str : strArgs) {
    cArgs.emplace_back(str.c_str());
}

execv("/usr/bin/ssh", (const char **)&cArgs.front());