How a interactive program knows the shell/terminal from which it is launched-CodePudding

I have a client program that can be executed in a linux terminal. The client sends this message to the server, and immediately dies once it receives the ack from the server:

struct Msg {
  char my_id[16];
};

The server just appends this my_id to a log file.

The thing is, I want Msg::my_id to be the same across the terminal/shell the client is executed from. How would I do this?

Say, I am a Linux user, and open two terminals: terminals X and Y.

I ran my client from X three times, and from Y twice. In that case, what should I add to the client in order for me to see three Xs and two Ys in the server side log file?

One thing I can think of is to take the ppid and send it. Would this always work? If not, what'd be better alternatives?

CodePudding user response：

@Author,

Proceed based on comment from Barmar.
I thought of sharing:
    #include <unistd.h>
    #include <string.h>
    #if defined( CYGWIN_NT ) || defined( LINUX )
            #include <iostream>
            using namespace std;
    #else
            #include <iostream.h>
    #endif
    int main()
    {
            // SAMPLE PROGRAM.
            struct Msg
            {
                    char my_id[16];
            };
            Msg obj;
            // I am not handling fork/... other related enhancements/updates at code.
            sprintf( obj.my_id, "%llu", getppid() );
            cout << obj.my_id << "\n";
            sprintf( obj.my_id, "%s", ttyname(STDIN_FILENO) );
            cout << obj.my_id << "\n";
            return 0;
    }
    $ g -DCYGWIN_NT getmy_id.cpp -o ./a.out
    $ ./a.out
    $ ./a.out
    47130
    /dev/pty0
    $ echo $$ current terminal pid
    47130 current terminal pid
We can also achieve the same using: user's last login:     How to get user's last login including the year in C