1	#!/usr/bin/env 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"$@"x}X
27	argv.py X${unset=x$@x}X # If you want OSH to split, write this
28	# osh
29	## STDOUT:
30	['Xx1', '2', '3', '4xX']
31	['Xx1', '2', '3', '4xX']
32	## END
33	## OK osh STDOUT:
34	['Xx1 2', '3 4xX']
35	['Xx1', '2', '3', '4xX']
36	## END
37
38	#### Quoted with array as default value
39	set -- '1 2' '3 4'
40	argv.py "X${unset=x"$@"x}X"
41	argv.py "X${unset=x$@x}X" # OSH is the same here
42	## STDOUT:
43	['Xx1 2 3 4xX']
44	['Xx1 2 3 4xX']
45	## END
46	## BUG bash STDOUT:
47	['Xx1', '2', '3', '4xX']
48	['Xx1 2 3 4xX']
49	## END
50	## OK osh STDOUT:
51	['Xx1 2', '3 4xX']
52	['Xx1 2 3 4xX']
53	## END
54
55	#### Assign default with array
56	set -- '1 2' '3 4'
57	argv.py X${unset=x"$@"x}X
58	argv.py "$unset"
59	## STDOUT:
60	['Xx1', '2', '3', '4xX']
61	['x1 2 3 4x']
62	## END
63	## OK osh STDOUT:
64	['Xx1 2', '3 4xX']
65	['x1 2 3 4x']
66	## END
67
68	#### Assign default value when empty
69	empty=''
70	${empty:=is empty}
71	echo $empty
72	## stdout: is empty
73
74	#### Assign default value when unset
75	${unset=is unset}
76	echo $unset
77	## stdout: is unset
78
79	#### Alternative value when empty
80	v=foo
81	empty=''
82	echo ${v:+v is not empty} ${empty:+is not empty}
83	## stdout: v is not empty
84
85	#### Alternative value when unset
86	v=foo
87	echo ${v+v is not unset} ${unset:+is not unset}
88	## stdout: v is not unset
89
90	#### Error when empty
91	empty=''
92	echo ${empty:?'is em'pty} # test eval of error
93	echo should not get here
94	## stdout-json: ""
95	## status: 1
96	## OK dash status: 2
97
98	#### Error when unset
99	echo ${unset?is empty}
100	echo should not get here
101	## stdout-json: ""
102	## status: 1
103	## OK dash status: 2
104
105	#### Error when unset
106	v=foo
107	echo ${v+v is not unset} ${unset:+is not unset}
108	## stdout: v is not unset