rewind()
Positions the current file to the beginning of input, resetting ARGF.lineno to zero.
ARGF.readline #=> "This is line one\n" ARGF.rewind #=> 0 ARGF.lineno #=> 0 ARGF.readline #=> "This is line one\n"
static VALUE argf_rewind(VALUE argf) { if (!next_argv()) { rb_raise(rb_eArgError, "no stream to rewind"); } ARGF_FORWARD(0, 0); return rb_io_rewind(ARGF.current_file); }