1
2	#### Process sub input
3	f=_tmp/process-sub.txt
4	{ echo 1; echo 2; echo 3; } > $f
5	cat <(head -n 2 $f) <(tail -n 2 $f)
6	## STDOUT:
7	1
8	2
9	2
10	3
11	## END
12
13	#### Process sub from external process to stdin
14	seq 3 > >(tac)
15	## STDOUT:
16	3
17	2
18	1
19	## END
20
21	#### Process sub from shell to stdin
22	{ echo 1; echo 2; echo 3; } > >(tac)
23	## STDOUT:
24	3
25	2
26	1
27	## END
28
29	#### Non-linear pipeline with >()
30	stdout_stderr() {
31	echo o1
32	echo o2
33
34	sleep 0.1 # Does not change order
35
36	{ echo e1;
37	echo warning: e2
38	echo e3;
39	} >& 2
40	}
41	stdout_stderr 2> >(grep warning) | tac >$TMP/out.txt
42	wait $! # this does nothing in bash 4.3, but probably does in bash 4.4.
43	echo OUT
44	cat $TMP/out.txt
45	# PROBLEM -- OUT comes first, and then 'warning: e2', and then 'o2 o1'. It
46	# looks like it's because nobody waits for the proc sub.
47	# http://lists.gnu.org/archive/html/help-bash/2017-06/msg00018.html
48	## STDOUT:
49	OUT
50	warning: e2
51	o2
52	o1
53	## END
54
55	#### $(<file) idiom with process sub
56	echo FOO >foo
57
58	# works in bash and zsh
59	echo $(<foo)
60
61	# this works in zsh, but not in bash
62	tr A-Z a-z < <(<foo)
63
64	cat < <(<foo; echo hi)
65
66	## STDOUT:
67	FOO
68	hi
69	## END
70	## OK zsh STDOUT:
71	FOO
72	foo
73	FOO
74	hi
75	## END
76
77	#### status code is available
78	cat <(seq 2; exit 2) <(seq 3; exit 3)
79	echo status=${_process_sub_status[@]}
80	echo done
81
82	## STDOUT:
83	1
84	2
85	1
86	2
87	3
88	status=2 3
89	done
90	## END
91	## N-I bash/zsh STDOUT:
92	1
93	2
94	1
95	2
96	3
97	status=
98	done
99	## END
100
101	#### shopt -s process_sub_fail
102
103	cat <(echo a; exit 2) <(echo b; exit 3)
104	echo status=$? ps=${_process_sub_status[@]}
105
106	echo __
107	shopt -s process_sub_fail
108
109	cat <(echo a; exit 2) <(echo b; exit 3)
110	echo status=$? ps=${_process_sub_status[@]}
111
112	# Now exit because of it
113	set -o errexit
114
115	cat <(echo a; exit 2) <(echo b; exit 3)
116	echo status=$? ps=${_process_sub_status[@]}
117
118	## status: 3
119	## STDOUT:
120	a
121	b
122	status=0 ps=2 3
123	__
124	a
125	b
126	status=3 ps=2 3
127	a
128	b
129	## END
130	## N-I bash/zsh status: 0
131	## N-I bash/zsh STDOUT:
132	a
133	b
134	status=0 ps=
135	__
136	a
137	b
138	status=0 ps=
139	a
140	b
141	status=0 ps=
142	## END
143
144	#### process subs and pipelines together
145
146	# zsh is very similar to bash, but don't bother with the assertions
147	case $SH in (zsh) exit ;; esac
148
149
150	f() {
151	cat <(seq 1; exit 1) | {
152	cat <(seq 2; exit 2) <(seq 3; exit 3)
153
154	# 2022-11 workaround for race condition: sometimes we get pipeline=141 4
155	# instead of pipeline=0 4, which means that the first 'cat' got SIGPIPE.
156	# If we make this part of the pipeline take longer, then 'cat' should have
157	# a chance to finish.
158
159	sleep 0.01
160
161	(exit 4)
162	}
163	echo status=$?
164	echo process_sub=${_process_sub_status[@]}
165	echo pipeline=${_pipeline_status[@]}
166	echo __
167	}
168
169	f
170
171	## STDOUT:
172	1
173	2
174	1
175	2
176	3
177	status=4
178	process_sub=2 3
179	pipeline=0 4
180	__
181	## END
182	## N-I bash STDOUT:
183	1
184	2
185	1
186	2
187	3
188	status=4
189	process_sub=
190	pipeline=
191	__
192	## END
193	## N-I zsh stdout-json: ""
194
195
196	#### process sub in background &
197
198	cat <(seq 3; sleep 0.1) & wait
199
200	echo sync
201
202	# This one escapes, and the shell should still exit
203	cat <(sleep 0.1) &
204
205	echo fork
206
207	## STDOUT:
208	1
209	2
210	3
211	sync
212	fork
213	## END