1	#!/bin/bash
2
3	### Lazy Evaluation of Alternative
4	i=0
5	x=x
6	echo ${x:-$((i++))}
7	echo $i
8	echo ${undefined:-$((i++))}
9	echo $i # i is one because the alternative was only evaluated once
10	# status: 0
11	# stdout-json: "x\n0\n0\n1\n"
12	# N-I dash status: 2
13	# N-I dash stdout-json: "x\n0\n"
14
15	### Default value when empty
16	empty=''
17	echo ${empty:-is empty}
18	# stdout: is empty
19
20	### Default value when unset
21	echo ${unset-is unset}
22	# stdout: is unset
23
24	### Unquoted with array as default value
25	set -- '1 2' '3 4'
26	argv.py X${unset=x"$@"x}X
27	# stdout: ['Xx1', '2', '3', '4xX']
28
29	### Quoted with array as default value
30	set -- '1 2' '3 4'
31	argv.py "X${unset=x"$@"x}X"
32	# stdout: ['Xx1 2 3 4xX']
33	# BUG bash stdout: ['Xx1', '2', '3', '4xX']
34
35	### Assign default value when empty
36	empty=''
37	${empty:=is empty}
38	echo $empty
39	# stdout: is empty
40
41	### Assign default value when unset
42	${unset=is unset}
43	echo $unset
44	# stdout: is unset
45
46	### Assign default with array
47	# HMMMM osh stdout-json: "['Xx1 2', '3 4xX']\n['x1 2 3 4x']\n"
48	# I think OSH diverges here because VTest is different than VOp1?
49	# I parse all the arg words the same way.
50	set -- '1 2' '3 4'
51	argv.py X${unset=x"$@"x}X
52	argv.py "$unset"
53	# stdout-json: "['Xx1', '2', '3', '4xX']\n['x1 2 3 4x']\n"
54
55	### Alternative value when empty
56	v=foo
57	empty=''
58	echo ${v:+v is not empty} ${empty:+is not empty}
59	# stdout: v is not empty
60
61	### Alternative value when unset
62	v=foo
63	echo ${v+v is not unset} ${unset:+is not unset}
64	# stdout: v is not unset
65
66	### Error when empty
67	empty=''
68	${empty:?is empty}
69	# status: 1
70	# OK dash status: 2
71
72	### Error when unset
73	${unset?is empty}
74	# status: 1
75	# OK dash status: 2
76
77	### Error when unset
78	v=foo
79	echo ${v+v is not unset} ${unset:+is not unset}
80	# stdout: v is not unset