1# $NetBSD: var-op-shell.mk,v 1.6 2022/01/10 20:32:29 rillig Exp $
2#
3# Tests for the != variable assignment operator, which runs its right-hand
4# side through the shell.
5
6# The variable OUTPUT gets the output from running the shell command.
7OUTPUT!=	echo "success"'ful'
8.if ${OUTPUT} != "successful"
9.  error
10.endif
11
12# Since 2014-08-20, the output of the shell command may be empty.
13#
14# On 1996-05-29, when the '!=' assignment operator and Cmd_Exec were added,
15# an empty output produced the error message "Couldn't read shell's output
16# for \"%s\"".
17#
18# The error message is still in Cmd_Exec but reserved for technical errors.
19# It may be possible to trigger the error message by killing the shell after
20# reading part of its output.
21OUTPUT!=	true
22.if ${OUTPUT} != ""
23.  error
24.endif
25
26# The output of a shell command that failed is processed nevertheless.
27# Unlike the other places that run external commands (expression modifier
28# '::!=', expression modifier ':!...!'), a failed command generates only a
29# warning, not an "error".  These "errors" are ignored in default mode, for
30# compatibility, but not in lint mode (-dL).
31OUTPUT!=	echo "failed"; false
32.if ${OUTPUT} != "failed"
33.  error
34.endif
35
36# A command with empty output may fail as well.
37OUTPUT!=	false
38.if ${OUTPUT} != ""
39.  error
40.endif
41
42# In the output of the command, each newline is replaced with a space.
43# Except for the very last one, which is discarded.
44OUTPUT!=	echo "line 1"; echo "line 2"
45.if ${OUTPUT} != "line 1 line 2"
46.  error
47.endif
48
49# A failing command in the middle results in the exit status 0, which in the
50# end means that the whole sequence of commands succeeded.
51OUTPUT!=	echo "before"; false; echo "after"
52.if ${OUTPUT} != "before after"
53.  error
54.endif
55
56# This should result in a warning about "exited on a signal".
57# This used to be kill -14 (SIGALRM), but that stopped working on
58# Darwin18 after recent update.
59OUTPUT!=	kill $$$$
60.if ${OUTPUT} != ""
61.  error
62.endif
63
64# A nonexistent command produces a non-zero exit status.
65OUTPUT!=	/bin/no/such/command
66.if ${OUTPUT} != ""
67.  error
68.endif
69
70# The output from the shell's stderr is not captured, it just passes through.
71OUTPUT!=	echo "stdout"; echo "stderr" 1>&2
72.if ${OUTPUT} != "stdout"
73.  error
74.endif
75
76# The 8 dollar signs end up as 4 dollar signs when expanded.  The shell sees
77# the command "echo '$$$$'".  The 4 dollar signs are stored in OUTPUT, and
78# when that variable is expanded, they expand to 2 dollar signs.
79OUTPUT!=	echo '$$$$$$$$'
80.if ${OUTPUT} != "\$\$"
81.  error
82.endif
83
84
85# As a debugging aid, log the exact command that is run via the shell.
86.MAKEFLAGS: -dv
87OUTPUT!=	echo '$$$$$$$$'
88.MAKEFLAGS: -d0
89
90all:
91