skip_to (file_offset file_pos, lin file_line)
{
    FILE *i = pfp;
    FILE *o = stdout;
    int c;

    assert(p_base <= file_pos);
    if ((verbosity == VERBOSE || !inname) && p_base < file_pos) {
	Fseek (i, p_base, SEEK_SET);
	say ("The text leading up to this was:\n--------------------------\n");

	while (file_tell (i) < file_pos)
	  {
	    putc ('|', o);
	    do
	      {
		if ((c = getc (i)) == EOF)
		  read_fatal ();
		putc (c, o);
	      }
	    while (c != '\n');
	  }

	say ("--------------------------\n");
    }
    else
	Fseek (i, file_pos, SEEK_SET);
    p_input_line = file_line - 1;
}

The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.