I am trying to create a simple GTK application. I would like to write things on the GUI as soon as certain files are created by different processes. I guess I cannot do a while(true) in the parent process, because that would freeze the GUI. Instead, I am trying to fork, check if files are present and manipulate the GUI, but it does not seem to work, my clumsy code is the following:
int check_for_files(){ FILE *fp; int files_set; char ch; files_set = 0; while(!files_set){ fp = fopen("file", "r"); if(fp != NULL){ content_length = 0; while(ch=getc(fp) != EOF){ content_length++; } fclose(fp); files_set = 1; return files_set; } else{ files_set = 0; } } return 1; } int main(int argc, char *argv[]) { // Main function the get the application UI GtkWidget *window; GdkPixbuf *icon; GtkWidget *grid; gtk_init(&argc, &argv); window = gtk_window_new(GTK_WINDOW_TOPLEVEL); gtk_window_set_default_size(GTK_WINDOW(window), 500, 300); gtk_container_set_border_width(GTK_CONTAINER(window), 15); gtk_window_set_position(GTK_WINDOW(window), GTK_WIN_POS_CENTER); int pid = fork(); if (pid == 0){ int files_set = check_for_files(); printf("files outside: %d\n",files_set); gtk_window_set_title(GTK_WINDOW(window), "Files are present!"); } else{ icon = create_pixbuf("net.png"); gtk_window_set_icon(GTK_WINDOW(window), icon); // Get the grid get_grid(window); gtk_widget_show_all(window); g_signal_connect(G_OBJECT(window), "destroy", G_CALLBACK(gtk_main_quit), NULL); g_object_unref(icon); gtk_main(); } } 
g_idle_add()is your friend.