Easiest way to make lua script wait/pause/sleep/block for a few seconds?

If you happen to use LuaSocket in your project, or just have it installed and don't mind to use it, you can use the socket.sleep(time) function which sleeps for a given amount of time (in seconds).

This works both on Windows and Unix, and you do not have to compile additional modules.

I should add that the function supports fractional seconds as a parameter, i.e. socket.sleep(0.5) will sleep half a second. It uses Sleep() on Windows and nanosleep() elsewhere, so you may have issues with Windows accuracy when time gets too low.

[I was going to post this as a comment on John Cromartie's post, but didn't realize you couldn't use formatting in a comment.]

I agree. Dropping it to a shell with os.execute() will definitely work but in general making shell calls is expensive. Wrapping some C code will be much quicker at run-time. In C/C++ on a Linux system, you could use:

static int lua_sleep(lua_State *L)
{
    int m = static_cast<int> (luaL_checknumber(L,1));
    usleep(m * 1000); 
    // usleep takes microseconds. This converts the parameter to milliseconds. 
    // Change this as necessary. 
    // Alternatively, use 'sleep()' to treat the parameter as whole seconds. 
    return 0;
}

Then, in main, do:

lua_pushcfunction(L, lua_sleep);
lua_setglobal(L, "sleep");

where "L" is your lua_State. Then, in your Lua script called from C/C++, you can use your function by calling:

sleep(1000) -- Sleeps for one second