1	#!/usr/bin/env bash
2	#
3	# NOTE:
4	# - $! is tested in background.test.sh
5	# - $- is tested in sh-options
6	#
7	# TODO: It would be nice to make a table, like:
8	#
9	# $$ $BASHPID $PPID $SHLVL $BASH_SUBSHELL
10	# X
11	# (Subshell, Command Sub, Pipeline, Spawn $0)
12	#
13	# And see whether the variable changed.
14
15	#### $PWD is set
16	# Just test that it has a slash for now.
17	echo $PWD | grep /
18	## status: 0
19
20	#### $PWD is not only set, but exported
21	env | grep PWD
22	## status: 0
23	## BUG mksh status: 1
24
25	#### $HOME is NOT set
26	case $SH in *zsh) echo 'zsh sets HOME'; exit ;; esac
27
28	home=$(echo $HOME)
29	test "$home" = ""
30	echo status=$?
31
32	env | grep HOME
33	echo status=$?
34
35	# not in interactive shell either
36	$SH -i -c 'echo $HOME' | grep /
37	echo status=$?
38
39	## STDOUT:
40	status=0
41	status=1
42	status=1
43	## END
44	## BUG zsh STDOUT:
45	zsh sets HOME
46	## END
47
48
49	#### $1 .. $9 are scoped, while $0 is not
50	func() { echo $0 $1 $2 | sed -e 's/.*sh/sh/'; }
51	func a b
52	## stdout: sh a b
53	## BUG zsh stdout: func a b
54
55	#### $?
56	echo $? # starts out as 0
57	sh -c 'exit 33'
58	echo $?
59	## stdout-json: "0\n33\n"
60	## status: 0
61
62	#### $#
63	set -- 1 2 3 4
64	echo $#
65	## stdout: 4
66	## status: 0
67
68	#### $_
69	# This is bash-specific.
70	echo hi
71	echo $_
72	## stdout-json: "hi\nhi\n"
73	## N-I dash/mksh stdout-json: "hi\n\n"
74
75	#### $$ looks like a PID
76	# Just test that it has decimal digits
77	echo $$ | egrep '[0-9]+'
78	## status: 0
79
80	#### $$ doesn't change with subshell or command sub
81	# Just test that it has decimal digits
82	set -o errexit
83	die() {
84	echo 1>&2 "$@"; exit 1
85	}
86	parent=$$
87	test -n "$parent" || die "empty PID in parent"
88	( child=$$
89	test -n "$child" || die "empty PID in subshell"
90	test "$parent" = "$child" || die "should be equal: $parent != $child"
91	echo 'subshell OK'
92	)
93	echo $( child=$$
94	test -n "$child" || die "empty PID in command sub"
95	test "$parent" = "$child" || die "should be equal: $parent != $child"
96	echo 'command sub OK'
97	)
98	exit 3 # make sure we got here
99	## status: 3
100	## STDOUT:
101	subshell OK
102	command sub OK
103	## END
104
105	#### $BASHPID DOES change with subshell and command sub
106	set -o errexit
107	die() {
108	echo 1>&2 "$@"; exit 1
109	}
110	parent=$BASHPID
111	test -n "$parent" || die "empty BASHPID in parent"
112	( child=$BASHPID
113	test -n "$child" || die "empty BASHPID in subshell"
114	test "$parent" != "$child" || die "should not be equal: $parent = $child"
115	echo 'subshell OK'
116	)
117	echo $( child=$BASHPID
118	test -n "$child" || die "empty BASHPID in command sub"
119	test "$parent" != "$child" ||
120	die "should not be equal: $parent = $child"
121	echo 'command sub OK'
122	)
123	exit 3 # make sure we got here
124	## status: 3
125	## STDOUT:
126	subshell OK
127	command sub OK
128	## END
129	## N-I dash/zsh status: 1
130	## N-I dash/zsh stdout-json: ""
131
132	#### Background PID $! looks like a PID
133	sleep 0.01 &
134	pid=$!
135	wait
136	echo $pid | egrep '[0-9]+' >/dev/null
137	echo status=$?
138	## stdout: status=0
139
140	#### $PPID
141	echo $PPID | egrep '[0-9]+'
142	## status: 0
143
144	# NOTE: There is also $BASHPID
145
146	#### $PIPESTATUS
147	echo hi | sh -c 'cat; exit 33' | wc -l >/dev/null
148	argv.py "${PIPESTATUS[@]}"
149	## status: 0
150	## STDOUT:
151	['0', '33', '0']
152	## END
153	## N-I dash stdout-json: ""
154	## N-I dash status: 2
155	## N-I zsh STDOUT:
156	['']
157	## END
158
159	#### $RANDOM
160	expr $0 : '.*/osh$' && exit 99 # Disabled because of spec-runner.sh issue
161	echo $RANDOM | egrep '[0-9]+'
162	## status: 0
163	## N-I dash status: 1
164
165	#### $UID and $EUID
166	# These are both bash-specific.
167	set -o errexit
168	echo $UID | egrep -o '[0-9]+' >/dev/null
169	echo $EUID | egrep -o '[0-9]+' >/dev/null
170	echo status=$?
171	## stdout: status=0
172	## N-I dash/mksh stdout-json: ""
173	## N-I dash/mksh status: 1
174
175	#### $OSTYPE is non-empty
176	test -n "$OSTYPE"
177	echo status=$?
178	## STDOUT:
179	status=0
180	## END
181	## N-I dash/mksh STDOUT:
182	status=1
183	## END
184
185	#### $HOSTNAME
186	test "$HOSTNAME" = "$(hostname)"
187	echo status=$?
188	## STDOUT:
189	status=0
190	## END
191	## N-I dash/mksh/zsh STDOUT:
192	status=1
193	## END
194
195	#### $LINENO is the current line, not line of function call
196	echo $LINENO # first line
197	g() {
198	argv.py $LINENO # line 3
199	}
200	f() {
201	argv.py $LINENO # line 6
202	g
203	argv.py $LINENO # line 8
204	}
205	f
206	## STDOUT:
207	1
208	['6']
209	['3']
210	['8']
211	## END
212	## BUG zsh STDOUT:
213	1
214	['1']
215	['1']
216	['3']
217	## END
218	## BUG dash STDOUT:
219	1
220	['2']
221	['2']
222	['4']
223	## END
224
225	#### $LINENO for [[
226	echo one
227	[[ $LINENO -eq 2 ]] && echo OK
228	## STDOUT:
229	one
230	OK
231	## END
232	## N-I dash status: 127
233	## N-I dash stdout: one
234	## N-I mksh status: 1
235	## N-I mksh stdout: one
236
237	#### $LINENO for ((
238	echo one
239	(( x = LINENO ))
240	echo $x
241	## STDOUT:
242	one
243	2
244	## END
245	## N-I dash stdout-json: "one\n\n"
246
247	#### $LINENO in for loop
248	# hm bash doesn't take into account the word break. That's OK; we won't either.
249	echo one
250	for x in \
251	$LINENO zzz; do
252	echo $x
253	done
254	## STDOUT:
255	one
256	2
257	zzz
258	## END
259	## OK mksh STDOUT:
260	one
261	1
262	zzz
263	## END
264
265	#### $LINENO in other for loops
266	set -- a b c
267	for x; do
268	echo $LINENO $x
269	done
270	## STDOUT:
271	3 a
272	3 b
273	3 c
274	## END
275
276	#### $LINENO in for (( loop
277	# This is a real edge case that I'm not sure we care about. We would have to
278	# change the span ID inside the loop to make it really correct.
279	echo one
280	for (( i = 0; i < $LINENO; i++ )); do
281	echo $i
282	done
283	## STDOUT:
284	one
285	0
286	1
287	## END
288	## N-I dash stdout: one
289	## N-I dash status: 2
290	## BUG mksh stdout: one
291	## BUG mksh status: 1
292
293	#### $LINENO for assignment
294	a1=$LINENO a2=$LINENO
295	b1=$LINENO b2=$LINENO
296	echo $a1 $a2
297	echo $b1 $b2
298	## STDOUT:
299	1 1
300	2 2
301	## END
302