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	# $$ $BASHPID $PPID $SHLVL $BASH_SUBSHELL
10	# X
11	# (Subshell, Command Sub, Pipeline, Spawn $0)
12	#
13	# And see whether the variable changed.
14
15	#### $PWD is set
16	# Just test that it has a slash for now.
17	echo $PWD | grep /
18	## status: 0
19
20	#### $PWD is not only set, but exported
21	env | grep PWD
22	## status: 0
23	## BUG mksh status: 1
24
25	#### $HOME is NOT set
26	case $SH in *zsh) echo 'zsh sets HOME'; exit ;; esac
27
28	home=$(echo $HOME)
29	test "$home" = ""
30	echo status=$?
31
32	env | grep HOME
33	echo status=$?
34
35	# not in interactive shell either
36	$SH -i -c 'echo $HOME' | grep /
37	echo status=$?
38
39	## STDOUT:
40	status=0
41	status=1
42	status=1
43	## END
44	## BUG zsh STDOUT:
45	zsh sets HOME
46	## END
47
48
49	#### $1 .. $9 are scoped, while $0 is not
50	fun() { echo $0 $1 $2 | sed -e 's/.*sh/sh/'; }
51	fun a b
52	## stdout: sh a b
53	## BUG zsh stdout: fun a b
54
55	#### $?
56	echo $? # starts out as 0
57	sh -c 'exit 33'
58	echo $?
59	## STDOUT:
60	0
61	33
62	## END
63	## status: 0
64
65	#### $#
66	set -- 1 2 3 4
67	echo $#
68	## stdout: 4
69	## status: 0
70
71	#### $_
72	# This is bash-specific.
73	echo hi
74	echo $_
75	## stdout-json: "hi\nhi\n"
76	## N-I dash/mksh stdout-json: "hi\n\n"
77
78	#### $$ looks like a PID
79	# Just test that it has decimal digits
80	echo $$ | egrep '[0-9]+'
81	## status: 0
82
83	#### $$ doesn't change with subshell or command sub
84	# Just test that it has decimal digits
85	set -o errexit
86	die() {
87	echo 1>&2 "$@"; exit 1
88	}
89	parent=$$
90	test -n "$parent" || die "empty PID in parent"
91	( child=$$
92	test -n "$child" || die "empty PID in subshell"
93	test "$parent" = "$child" || die "should be equal: $parent != $child"
94	echo 'subshell OK'
95	)
96	echo $( child=$$
97	test -n "$child" || die "empty PID in command sub"
98	test "$parent" = "$child" || die "should be equal: $parent != $child"
99	echo 'command sub OK'
100	)
101	exit 3 # make sure we got here
102	## status: 3
103	## STDOUT:
104	subshell OK
105	command sub OK
106	## END
107
108	#### $BASHPID DOES change with subshell and command sub
109	set -o errexit
110	die() {
111	echo 1>&2 "$@"; exit 1
112	}
113	parent=$BASHPID
114	test -n "$parent" || die "empty BASHPID in parent"
115	( child=$BASHPID
116	test -n "$child" || die "empty BASHPID in subshell"
117	test "$parent" != "$child" || die "should not be equal: $parent = $child"
118	echo 'subshell OK'
119	)
120	echo $( child=$BASHPID
121	test -n "$child" || die "empty BASHPID in command sub"
122	test "$parent" != "$child" ||
123	die "should not be equal: $parent = $child"
124	echo 'command sub OK'
125	)
126	exit 3 # make sure we got here
127	## status: 3
128	## STDOUT:
129	subshell OK
130	command sub OK
131	## END
132	## N-I dash/zsh status: 1
133	## N-I dash/zsh stdout-json: ""
134
135	#### Background PID $! looks like a PID
136	sleep 0.01 &
137	pid=$!
138	wait
139	echo $pid | egrep '[0-9]+' >/dev/null
140	echo status=$?
141	## stdout: status=0
142
143	#### $PPID
144	echo $PPID | egrep '[0-9]+'
145	## status: 0
146
147	# NOTE: There is also $BASHPID
148
149	#### $PIPESTATUS
150	echo hi | sh -c 'cat; exit 33' | wc -l >/dev/null
151	argv.py "${PIPESTATUS[@]}"
152	## status: 0
153	## STDOUT:
154	['0', '33', '0']
155	## END
156	## N-I dash stdout-json: ""
157	## N-I dash status: 2
158	## N-I zsh STDOUT:
159	['']
160	## END
161
162	#### $RANDOM
163	expr $0 : '.*/osh$' && exit 99 # Disabled because of spec-runner.sh issue
164	echo $RANDOM | egrep '[0-9]+'
165	## status: 0
166	## N-I dash status: 1
167
168	#### $UID and $EUID
169	# These are both bash-specific.
170	set -o errexit
171	echo $UID | egrep -o '[0-9]+' >/dev/null
172	echo $EUID | egrep -o '[0-9]+' >/dev/null
173	echo status=$?
174	## stdout: status=0
175	## N-I dash/mksh stdout-json: ""
176	## N-I dash/mksh status: 1
177
178	#### $OSTYPE is non-empty
179	test -n "$OSTYPE"
180	echo status=$?
181	## STDOUT:
182	status=0
183	## END
184	## N-I dash/mksh STDOUT:
185	status=1
186	## END
187
188	#### $HOSTNAME
189	test "$HOSTNAME" = "$(hostname)"
190	echo status=$?
191	## STDOUT:
192	status=0
193	## END
194	## N-I dash/mksh/zsh STDOUT:
195	status=1
196	## END
197
198	#### $LINENO is the current line, not line of function call
199	echo $LINENO # first line
200	g() {
201	argv.py $LINENO # line 3
202	}
203	f() {
204	argv.py $LINENO # line 6
205	g
206	argv.py $LINENO # line 8
207	}
208	f
209	## STDOUT:
210	1
211	['6']
212	['3']
213	['8']
214	## END
215	## BUG zsh STDOUT:
216	1
217	['1']
218	['1']
219	['3']
220	## END
221	## BUG dash STDOUT:
222	1
223	['2']
224	['2']
225	['4']
226	## END
227
228	#### $LINENO for [[
229	echo one
230	[[ $LINENO -eq 2 ]] && echo OK
231	## STDOUT:
232	one
233	OK
234	## END
235	## N-I dash status: 127
236	## N-I dash stdout: one
237	## N-I mksh status: 1
238	## N-I mksh stdout: one
239
240	#### $LINENO for ((
241	echo one
242	(( x = LINENO ))
243	echo $x
244	## STDOUT:
245	one
246	2
247	## END
248	## N-I dash stdout-json: "one\n\n"
249
250	#### $LINENO in for loop
251	# hm bash doesn't take into account the word break. That's OK; we won't either.
252	echo one
253	for x in \
254	$LINENO zzz; do
255	echo $x
256	done
257	## STDOUT:
258	one
259	2
260	zzz
261	## END
262	## OK mksh STDOUT:
263	one
264	1
265	zzz
266	## END
267
268	#### $LINENO in other for loops
269	set -- a b c
270	for x; do
271	echo $LINENO $x
272	done
273	## STDOUT:
274	3 a
275	3 b
276	3 c
277	## END
278
279	#### $LINENO in for (( loop
280	# This is a real edge case that I'm not sure we care about. We would have to
281	# change the span ID inside the loop to make it really correct.
282	echo one
283	for (( i = 0; i < $LINENO; i++ )); do
284	echo $i
285	done
286	## STDOUT:
287	one
288	0
289	1
290	## END
291	## N-I dash stdout: one
292	## N-I dash status: 2
293	## BUG mksh stdout: one
294	## BUG mksh status: 1
295
296	#### $LINENO for assignment
297	a1=$LINENO a2=$LINENO
298	b1=$LINENO b2=$LINENO
299	echo $a1 $a2
300	echo $b1 $b2
301	## STDOUT:
302	1 1
303	2 2
304	## END
305