1	#!/bin/bash
2
3	### (( )) result
4	(( 1 )) && echo True
5	(( 0 )) || echo False
6	# stdout-json: "True\nFalse\n"
7
8	### negative number is true
9	(( -1 )) && echo True
10	# stdout: True
11
12	### (( )) in if statement
13	if (( 3 > 2)); then
14	echo True
15	fi
16	# stdout: True
17
18	### (( ))
19	# What is the difference with this and let? One difference: spaces are allowed.
20	(( x = 1 ))
21	(( y = x + 2 ))
22	echo $x $y
23	# stdout: 1 3
24
25	### (( )) with arrays
26	a=(4 5 6)
27	(( sum = a[0] + a[1] + a[2] ))
28	echo $sum
29	# stdout: 15
30	# OK zsh stdout: 9
31
32	### (( )) with error
33	(( a = 0 )) || echo false
34	(( b = 1 )) && echo true
35	(( c = -1 )) && echo true
36	echo $((a + b + c))
37	# stdout-json: "false\ntrue\ntrue\n0\n"