**Use case**

It prints:
```
ClickHouse has been successfully installed.

Start clickhouse-server with:
 sudo clickhouse start
```

But if clickhouse-server is already running, let's print:
```
ClickHouse has been successfully installed.

Restart clickhouse-server with:
 sudo clickhouse restart
```
{
        if (fs::exists(pid_file))
        {
            ReadBufferFromFile in(pid_file.string());
            UInt64 pid;
            if (tryReadIntText(pid, in))
            {
                fmt::print("{} file exists and contains pid = {}.\n", pid_file.string(), pid);
                if (0 == kill(pid, 0))
                {
                    fmt::print("The process with pid = {} is already running.\n", pid);
                    return 2;
                }
            }
            else
            {
                fmt::print("{} file exists but damaged, ignoring.\n", pid_file.string());
                fs::remove(pid_file);
            }
        }
        else
        {
            
            
            fs::path pid_path = pid_file;
            pid_path.remove_filename();