How to pass system(cmd) into a specific process?

socialjazz · 10-06-2006, 02:28 AM

Lets say i have a simple program

void main(void)
{
key = read_key();
if (key == 'q')
printf ("q is pressed\n");
else
printf ("not q is pressed\n");
}

read_key() will detect a key pressed in the console.

I execute this application by using system(app_name);
I also know the PID (process ID) of this app running

how do i use C programming to simulate a key pressed in the application running?

Note that i only invoke the application to run by using the shell command system(app_name).

jlliagre · 10-06-2006, 05:00 AM

Quote:

Originally Posted by socialjazz

read_key() will detect a key pressed in the console.

how does it detect a keypress ?

Quote:

I execute this application by using system(app_name);
I also know the PID (process ID) of this app running

how do i use C programming to simulate a key pressed in the application running?

The simpler way would be by having read_key() to support an alternative input method.

randyding · 10-06-2006, 11:35 PM

You have to use popen("appname","w") instead of system("appname"). Then with the handle returned by popen() you can fwrite() the keypress to the process's stdin. Call pclose() when done.

Edit: this may also work though I haven't tried it.
Try calling system("echo X | appname");
I'd be surprised if it doesn't work.