1	#!/bin/bash
2
3	### $?
4	echo $? # starts out as 0
5	sh -c 'exit 33'
6	echo $?
7	# stdout-json: "0\n33\n"
8	# status: 0
9
10	### $#
11	set -- 1 2 3 4
12	echo $#
13	# stdout: 4
14	# status: 0
15
16	### $-
17	# dash's behavior seems most sensible here?
18	$SH -o nounset -c 'echo $-'
19	# OK bash stdout: huBc
20	# OK dash stdout: u
21	# OK mksh stdout: uhc
22	# status: 0
23
24	### $_
25	# This is bash-specific.
26	echo hi
27	echo $_
28	# stdout-json: "hi\nhi\n"
29	# N-I dash/mksh stdout-json: "hi\n\n"
30
31	### PID $$
32	# Just test that it has decimal digits
33	echo $$ | egrep '[0-9]+'
34	# status: 0
35
36	### Background PID $!
37	# Just test that it has decimal digits
38	sleep 0.01 &
39	echo $! | egrep '[0-9]+'
40	wait
41	# status: 0
42
43	### $PPID
44	expr $0 : '.*/osh$' && exit 99 # Disabled because of spec-runner.sh issue
45	echo $PPID | egrep '[0-9]+'
46	# Disabled because of spec-runner.sh issue: bash sets it for osh
47	# status: 0
48
49	# NOTE: There is also $BASHPID
50
51	### $PIPESTATUS
52	echo hi | sh -c 'cat; exit 33' | wc -l >/dev/null
53	argv.py "${PIPESTATUS[@]}"
54	# status: 0
55	# stdout: ['0', '33', '0']
56	# N-I dash stdout-json: ""
57	# N-I dash status: 2
58
59	### $PWD
60	cd /
61	echo $PWD
62	# status: 0
63	# stdout: /
64
65	### $RANDOM
66	expr $0 : '.*/osh$' && exit 99 # Disabled because of spec-runner.sh issue
67	echo $RANDOM | egrep '[0-9]+'
68	# status: 0
69	# N-I dash status: 1