Add 'i' to $- when the shell is interactive.

Fixes issue #118.

bin/oil.py

@@ -262,23 +262,23 @@ def OshMain(argv0, argv, login_shell):
  if opts.c is not None:
    arena.PushSource('<command string>')
    line_reader = reader.StringLineReader(opts.c, arena)
    interactive = False
    if opts.i:  # -c and -i can be combined
      exec_opts.interactive = True
  elif opts.i:  # force interactive
    arena.PushSource('<stdin -i>')
    line_reader = reader.InteractiveLineReader(OSH_PS1, arena)
    interactive = True
    exec_opts.interactive = True
  else:
    try:
      script_name = argv[opt_index]
    except IndexError:
      if sys.stdin.isatty():
        arena.PushSource('<interactive>')
        line_reader = reader.InteractiveLineReader(OSH_PS1, arena)
        interactive = True
        exec_opts.interactive = True
      else:
        arena.PushSource('<stdin>')
        line_reader = reader.FileLineReader(sys.stdin, arena)
        interactive = False
    else:
      arena.PushSource(script_name)
      try:
@@ -287,13 +287,12 @@ def OshMain(argv0, argv, login_shell):
        util.error("Couldn't open %r: %s", script_name, os.strerror(e.errno))
        return 1
      line_reader = reader.FileLineReader(f, arena)
      interactive = False

  # TODO: assert arena.NumSourcePaths() == 1
  # TODO: .rc file needs its own arena.
  w_parser, c_parser = parse_lib.MakeParser(line_reader, arena)

  if interactive:
  if exec_opts.interactive:
    # NOTE: We're using a different evaluator here.  The completion system can
    # also run functions... it gets the Executor through Executor._Complete.
    if HAVE_READLINE:

core/state.py

@@ -104,6 +104,10 @@ def __init__(self, mem):
    """
    self.mem = mem

    # Depends on the shell invocation (sh -i, etc.)  This is not technically an
    # 'set' option, but it appears in $-.
    self.interactive = False

    # set -o / set +o
    self.errexit = _ErrExit()  # -e
    self.nounset = False  # -u
@@ -169,6 +173,9 @@ def ErrExit(self):

  def GetDollarHyphen(self):
    chars = []
    if self.interactive:
      chars.append('i')

    if self.ErrExit():
      chars.append('e')
    if self.nounset:

spec/sh-options.test.sh

@@ -20,6 +20,14 @@ echo $-
# N-I dash stdout-json: ""
# N-I dash status: 2

### $- with interactive shell
$SH -c 'echo $-' | grep i || echo FALSE
$SH -i -c 'echo $-' | grep -q i && echo TRUE
## STDOUT:
FALSE
TRUE
## END

### sh -c
$SH -c 'echo hi'
# stdout: hi