machinesFile = getEnv("NIX_REMOTE_SYSTEMS", "/etc/nix/machines");
    machinesFileStat.st_ino = 0;
    machinesFileStat.st_mtime = 0;

void State::loadMachinesFile()

void State::parseMachines(const std::string & contents)

    string contents;
    if (pathExists(machinesFile)) {
        struct stat st;
        if (stat(machinesFile.c_str(), &st) != 0)
            throw SysError(format("getting stats about ‘%1%’") % machinesFile);
        if (st.st_ino == machinesFileStat.st_ino && st.st_mtime == machinesFileStat.st_mtime)
            return;
        printMsg(lvlDebug, "reloading machines");
        contents = readFile(machinesFile);
        machinesFileStat = st;
    } else {
        contents = "localhost " + concatStringsSep(",", localPlatforms)
            + " - " + int2String(settings.maxBuildJobs) + " 1";
    }

    string defaultMachinesFile = "/etc/nix/machines";
    auto machinesFiles = tokenizeString<std::vector<Path>>(
        getEnv("NIX_REMOTE_SYSTEMS", pathExists(defaultMachinesFile) ? defaultMachinesFile : ""), ":");
    if (machinesFiles.empty()) {
        parseMachines("localhost " + concatStringsSep(",", localPlatforms)
            + " - " + int2String(settings.maxBuildJobs) + " 1");
        return;
    }
    std::vector<struct stat> fileStats;
    fileStats.resize(machinesFiles.size());
    for (unsigned int n = 0; n < machinesFiles.size(); ++n) {
        auto & st(fileStats[n]);
        st.st_ino = st.st_mtime = 0;
    }
    auto readMachinesFiles = [&]() {
        /* Check if any of the machines files changed. */
        bool anyChanged = false;
        for (unsigned int n = 0; n < machinesFiles.size(); ++n) {
            Path machinesFile = machinesFiles[n];
            struct stat st;
            if (stat(machinesFile.c_str(), &st) != 0) {
                if (errno != ENOENT)
                    throw SysError(format("getting stats about ‘%1%’") % machinesFile);
                st.st_ino = st.st_mtime = 0;
            }
            auto & old(fileStats[n]);
            if (old.st_ino != st.st_ino || old.st_mtime != st.st_mtime)
                anyChanged = true;
            old = st;
        }
        if (!anyChanged) return;
        debug("reloading machines files");
        string contents;
        for (auto & machinesFile : machinesFiles) {
            try {
                contents += readFile(machinesFile);
                contents += '\n';
            } catch (SysError & e) {
                if (e.errNo != ENOENT) throw;
            }
        }
        parseMachines(contents);
    };

            readMachinesFiles();

            sleep(60);
            loadMachinesFile();

            sleep(30);

    loadMachinesFile();

    nix::Path machinesFile;
    struct stat machinesFileStat;

    /* (Re)load /etc/nix/machines. */
    void loadMachinesFile();

    void parseMachines(const std::string & contents);

    my $machinesConf = $ENV{"NIX_REMOTE_SYSTEMS"} || "/etc/nix/machines";
    # Read the list of machines.

    if (-e $machinesConf) {
        open CONF, "<$machinesConf" or die;

    my @machinesFiles = split /:/, ($ENV{"NIX_REMOTE_SYSTEMS"} || "/etc/nix/machines");
    for my $machinesFile (@machinesFiles) {
        next unless -e $machinesFile;
        open CONF, "<$machinesFile" or die;