cat.c

#include <gst/gst.h>

gboolean on_message(GstBus *bus, GstMessage *message, gpointer p)
{
	GMainLoop *mainloop = p;

	(void)bus;
	if ((GST_MESSAGE_TYPE(message) & GST_MESSAGE_EOS))
	    g_main_loop_quit(mainloop);

	return TRUE;
}

int main(int argc, char *argv[])
{
	GMainLoop *mainloop;
	GstElement *pipeline;
	GError *error = NULL;
	GstBus *bus;

	gst_init(&argc, &argv);

	mainloop = g_main_loop_new(NULL, FALSE);
	pipeline = gst_parse_launch("filesrc location=a.txt ! fdsink", &error);
	bus = gst_element_get_bus(pipeline);
	gst_bus_add_watch(bus, on_message, mainloop);

	gst_element_set_state(pipeline, GST_STATE_PLAYING);
	g_main_loop_run(mainloop);

	return 0;
}