The 'restart' option of the init script cannot restart CH if it was not able to shutdown in `shutdown_wait_unfinished` seconds.
```
# sudo /etc/init.d/clickhouse-server restart
/var/run/clickhouse-server/clickhouse-server.pid file exists and contains pid = 14388.
The process with pid = 14388 is running.
Sent terminate signal to process with pid 14388.
Waiting for server to stop
/var/run/clickhouse-server/clickhouse-server.pid file exists and contains pid = 14388.
The process with pid = 14388 is running.
Waiting for server to stop
...
/var/run/clickhouse-server/clickhouse-server.pid file exists and contains pid = 14388.
Waiting for server to stop
/var/run/clickhouse-server/clickhouse-server.pid file exists and contains pid = 14388.
Waiting for server to stop
...
/var/run/clickhouse-server/clickhouse-server.pid file exists and contains pid = 14388.
Will terminate forcefully.
Code: 425, e.displayText() = DB::ErrnoException: Cannot send kill signal, errno: 3, strerror: No such process (version 21.1.3.32 (official build))
```
The log:
```
2021.02.08 18:57:23.999226 [ 14388 ] {} <Information> Application: Closed connections. But 3 remain. Tip: To increase wait time add to config: <shutdown_wait_unfinished>60</shutdown_wait_unfinished>
2021.02.08 18:57:24.016684 [ 14388 ] {} <Information> Application: Will shutdown forcefully.
2021.02.08 18:58:28.478835 [ 23658 ] {} <Information> Application: Will watch for the process with pid 23659
2021.02.08 18:58:28.478962 [ 23659 ] {} <Information> Application: Forked a child process to watch
2021.02.08 18:58:28.479067 [ 23659 ] {} <Information> StatusFile: Status file /var/run/clickhouse-server/clickhouse-server.pid already exists - unclean restart. Contents: 14388
2021.02.08 18:58:28.479147 [ 23659 ] {} <Information> SentryWriter: Sending crash reports is disabled
2021.02.08 18:58:28.479183 [ 23659 ] {} <Trace> Pipe: Pipe capacity is 1.00 MiB
2021.02.08 18:58:28.532977 [ 23659 ] {} <Information> : Starting ClickHouse 21.1.3.32 with revision 54445, build id: 63BC1671E8C217170F9B6C6346099FD1F76E784F, PID 23659
2021.02.08 18:58:28.533059 [ 23659 ] {} <Information> Application: starting up
```

{
    auto sh = ShellCommand::execute(command);
    WriteBufferFromFileDescriptor wb_stdout(STDOUT_FILENO);
    WriteBufferFromFileDescriptor wb_stderr(STDERR_FILENO);
    copyData(sh->out, wb_stdout);
    copyData(sh->err, wb_stderr);
    if (throw_on_error)
    {
        sh->wait();
        return 0;
    }
    else
        return sh->tryWait();
}
static bool ask(std::string question)
{
    while (true)
    {
        std::string answer;
        std::cout << question;
        std::getline(std::cin, answer);
        if (!std::cin.good())
            return false;
        if (answer.empty() || answer == "n" || answer == "N")
            return false;
        if (answer == "y" || answer == "Y")
            return true;
    }
}
static bool filesEqual(std::string path1, std::string path2)