On Error Skip 1
Error "foo"
Print "MSG: " Mm.ErrMsg$, Mm.ErrNo
Error "bar"

> run
MSG: Error in line 2: foo        16
Error in line 4: bar
<newline>

> run
MSG: foo    16
bar

MMBASIC 0

/**
* Executes a system command and captures its STDOUT in a buffer.
*
* @param  cmd  system command to execute.
* @param  buf  buffer to capture output in, this will not be '\0' terminated.
* @param  sz   on entry size of buffer,
*              on return number of characters in buffer.
* @return      exit code of the executed system command.
*/
static int cmd_system_capture(char *cmd, char *buf, size_t *sz) {
   FILE *f = popen(cmd, "r");
   error_check();

   int i;
   for (i = 0; i < *sz; ++i) {
       int ch = fgetc(f);
       if (ch == EOF) break;
       buf[i] = (char) ch;
   }

   // Trim trailing whitespace and non-ASCII garbage.
   while (buf[i] < 33 || buf[i] > 126) i--;

   *sz = i + 1;

   return pclose(f);
}

MMBASIC 'opens MMBasic
MMBASIC "program.bas" ' opens MMBasic and immediately runs program.bas
MMBASIC "program" ' opens MMBasic and immediately runs program.bas
MMBASIC "program.bas",text ' opens MMBasic and immediately runs program.bas, passes text to the program as MM.CMDLINE$
MMBASIC "program",text ' opens MMBasic and immediately runs program.bas, passes text to the program as MM.CMDLINE$
MMBASIC  0 'opens MMBasic with audio disabled
MMBASIC 0 "program.bas" ' opens MMBasic and immediately runs program.bas with audio disabled
MMBASIC 0 "program" ' opens MMBasic and immediately runs program.bas with audio disabled
MMBASIC 0 "program.bas",text ' opens MMBasic and immediately runs program.bas, passes text to the program as MM.CMDLINE$ with audio disabled
MMBASIC 0 "program",text ' opens MMBasic and immediately runs program.bas, passes text to the program as MM.CMDLINE$ with audio disabled