How can new gnome terminal receive command in C

I have tried to write a program that run in ubuntu terminal .Program will open a new gnome terminal and run command in that new terminal to open new abcd.txt using vim.And then when i Ctrl+C in the first terminal which run the program ,new gnome terminal will shut vim down and have an announcement in the first terminal

I have tried system("`gnome-terminal`<< vim abcd.txt");

and this system("vim abcd.txt>>`gnome-terminal`");

but the new one terminal cannot recieve command

My full code

#include <stdio.h> 
#include <stdlib.h>
#include <unistd.h> 
#include <sys/wait.h> 
#include <pthread.h> 

int loop=1; 

void DEF() 
{ 
    system("kill -9 pidof vim"); 
    loop=0; 
}

void *subthreads(void *threadid) 
{ 
    loop=1; 
    long tid; 
    tid=(long)threadid; 
    system("`gnome-terminal`<< vim abcd.txt");
    signal(SIGINT,DEF); 
    while(loop){} 
    pthread_exit(NULL); 
}

void main() 
{ 
    int loop=1; 
    pthread_t threads; 
    int check; 
    long tID; 
    check= pthread_create(&threads,NULL,&subthreads,(void*)tID);
    while(loop){} 
    printf("Ctrl+C is pressed!\n");
}

Solution

Not sure what you are trying to achieve in the end. But here are a few ideas, starting from your code:

The terminal command (in system()) should be something like Mark Setchell pointed out, like for example system("gnome-terminal -e vim file.txt");
The system() command is blocking further execution of your code, so the call to signal() is not happening until you terminate the system() call.
pidof is not working on my Linux system. I would use pkill <program>. Still, that would kill all running instances of , for example vim or your terminal.
You are declaring the variable loop in the global scope first and then redeclaring it in main(). If you really want to use it as a global variable, it should just be loop=1 in main().
You are not using the variable tid for anything.

Here is an improved version of your program, with additional printf calls to explain to the user what is happening. I also used xterm and nano because I don't have gnome-terminal, and I didn't want to interfere with my running instance of vim. But it still is maybe not exactly what you are trying to do. The main problem is that system("xterm -e sh &") is blocking and when you press Ctrl-C, that system call will terminate xterm so that the def() function will do nothing when it is called later.

#include <stdio.h> 
#include <stdlib.h>
#include <unistd.h> 
#include <sys/wait.h> 
#include <pthread.h> 

int loop = 1;

void def()
{
    printf("In def\n");
    system("pkill xterm"); 
    loop=0; 
}

void *subthreads(void *threadid)
{
    printf("Starting subthread\n");
    loop = 1;
    long tid;
    tid = (long)threadid;
    signal(SIGINT, def);
    system("xterm -e sh -c nano &");   // Note: xterm will still exit when you press Ctrl-C
    printf("Terminal exited in subthread\n");
    while (loop);
    printf("Exited loop in subthread\n");
    pthread_exit(NULL);
}

void main()
{
    pthread_t threads;
    int check;
    long tID;
    check = pthread_create(&threads, NULL, &subthreads, (void*)tID);
    printf("In main after thread creation\n");
    while (loop);
    printf("Ctrl+C is pressed!\n");
}

Another option is to use fork() instead of pthread to split into a separate process. (Note that processes are like separate applications while threads are processor threads in the same application.)

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/wait.h>

void def()
{
    system("pkill nano");
    printf("def(): Killed nano\n");
}

int subprocess()
{
    signal(SIGINT, def);
    pid_t parent_id = getpid();  // Get process ID of main process
    fork();                      // Fork into two identical copies of the running app.
    if (getpid() != parent_id) {  // The part in the if block is only done in the second process!
        system("xterm -e sh -c nano &");
        printf("subprocess(): system call ended in forked process\n");
        exit(0);
    }
}

int main()
{
    subprocess();
    printf("Entering while loop in main process\n");
    while (1);
    printf("Exited main thread\n");
}

The one flaw with this version is the same as the previous one: when Ctrl-C is pressed, xterm/nano is killed and def() will subsequently do nothing except catch any Ctrl-C done afterwards.

If you explain further what your final goal is, maybe I can give some suggestions. Like, why do you want to start vim in a terminal from a C application and then kill vim? Do you want to kill the whole terminal or only vim?