Executing shell commands flickers a console

CrazyAmphibian · April 28, 2025, 2:45am

using io.popen or os.execute, on a windows release build causes command prompt to appear on screen for a very brief period.
The biggest issue is that, besides being jarring, most users are going to believe that the game contains a virus when they open it up and see 3 consoles flash.
why is this happening? if there’s no fix, are there alternative builtin functions to replace calls to those commands?

currently i am using them to get map files in a directory, as well as to delete other files that the program can create.

defold engine 1.9.2

britzl · April 28, 2025, 6:04am

These functions call straight to C and whatever happens is outside of our control. As an example, os.execute() will call system():

github.com/lua/lua

loslib.c

master


      
          #if !defined(l_system)
          #if defined(LUA_USE_IOS)
          /* Despite claiming to be ISO C, iOS does not implement 'system'. */
          #define l_system(cmd) ((cmd) == NULL ? 0 : -1)
          #else
          #define l_system(cmd)	system(cmd)  /* default definition */
          #endif
          #endif
          
          
          static int os_execute (lua_State *L) {
            const char *cmd = luaL_optstring(L, 1, NULL);
            int stat;
            errno = 0;
            stat = l_system(cmd);

       The system() library function behaves as if it used fork(2) to
       create a child process that executed the shell command specified
       in command using execl(3) as follows:

           execl("/bin/sh", "sh", "-c", command, (char *) NULL);

I would recommend that you use the functions of LuaFileSystem to get the files in a folder:

CrazyAmphibian · April 28, 2025, 7:04pm

fixes the issue on windows, but now it won’t run on linux because of a missing libc dependancy

britzl · April 28, 2025, 10:05pm

What’s the exact error you are getting and which Linux variant are you using?

CrazyAmphibian · April 28, 2025, 10:43pm

/home/frog/Desktop/conformer/build/x86_64-linux/dmengine: /lib/x86_64-linux-gnu/libc.so.6: version `GLIBC_2.33' not found (required by /home/frog/Desktop/conformer/build/x86_64-linux/dmengine)
/home/frog/Desktop/conformer/build/x86_64-linux/dmengine: /lib/x86_64-linux-gnu/libc.so.6: version `GLIBC_2.34' not found (required by /home/frog/Desktop/conformer/build/x86_64-linux/dmengine)

using linux mint version 20.3 (fork of ubuntu)

britzl · April 29, 2025, 5:14am

Ah, Ubuntu 20.04 will reach end of life on May 31 2025 which means that we will also no longer support it. We updated Defold ahead of time and we now build the engine using Ubuntu 22.04 LTS.