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#!/usr/bin/env bash |
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|
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#### recursive arith: one level |
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shopt -s eval_unsafe_arith |
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a='b=123' |
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echo $((a)) |
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## stdout: 123 |
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## N-I dash status: 2 |
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## N-I dash stdout-json: "" |
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## N-I yash stdout: b=123 |
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|
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#### recursive arith: two levels |
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shopt -s eval_unsafe_arith |
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a='b=c' c='d=123' |
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echo $((a)) |
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## stdout: 123 |
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## N-I dash status: 2 |
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## N-I dash stdout-json: "" |
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## N-I yash stdout: b=c |
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|
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#### recursive arith: short circuit &&, || |
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# Note: mksh R52 has a bug. Even though it supports a short circuit like |
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# "echo $((cond&&(a=1)))", it doesn't work with "x=a=1; echo |
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# $((cond&&x))". It is fixed at least in mksh R57. |
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# Note: "busybox sh" doesn't support short circuit. |
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shopt -s eval_unsafe_arith |
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a=b=123 |
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echo $((1||a)):$((b)) |
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echo $((0||a)):$((b)) |
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c=d=321 |
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echo $((0&&c)):$((d)) |
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echo $((1&&c)):$((d)) |
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## stdout-json: "1:0\n1:123\n0:0\n1:321\n" |
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## BUG mksh stdout-json: "1:123\n1:123\n0:321\n1:321\n" |
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## N-I ash stdout-json: "1:123\n1:123\n0:321\n1:321\n" |
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## N-I dash/yash status: 2 |
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## N-I dash/yash stdout-json: "1:0\n" |
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|
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#### recursive arith: short circuit ?: |
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# Note: "busybox sh" behaves strangely. |
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shopt -s eval_unsafe_arith |
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y=a=123 n=a=321 |
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echo $((1?(y):(n))):$((a)) |
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echo $((0?(y):(n))):$((a)) |
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## stdout-json: "123:123\n321:321\n" |
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## BUG ash stdout-json: "123:123\n321:123\n" |
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## N-I dash status: 2 |
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## N-I dash stdout-json: "" |
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## N-I yash stdout-json: "a=123:0\na=321:0\n" |
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|
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#### recursive arith: side effects |
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# In Zsh and Busybox sh, the side effect of inner arithmetic |
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# evaluations seems to take effect only after the whole evaluation. |
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shopt -s eval_unsafe_arith |
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a='b=c' c='d=123' |
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echo $((a,d)):$((d)) |
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## stdout: 123:123 |
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## BUG zsh/ash stdout: 0:123 |
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## N-I dash/yash status: 2 |
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## N-I dash/yash stdout-json: "" |
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|
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#### recursive arith: recursion |
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shopt -s eval_unsafe_arith |
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loop='i<=100&&(s+=i,i++,loop)' s=0 i=0 |
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echo $((a=loop,s)) |
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## stdout: 5050 |
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## N-I mksh status: 1 |
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## N-I mksh stdout-json: "" |
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## N-I ash/dash/yash status: 2 |
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## N-I ash/dash/yash stdout-json: "" |
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|
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#### recursive arith: array elements |
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shopt -s eval_unsafe_arith |
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text[1]='d=123' |
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text[2]='text[1]' |
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text[3]='text[2]' |
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echo $((a=text[3])) |
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## stdout: 123 |
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## N-I ash/dash/yash status: 2 |
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## N-I ash/dash/yash stdout-json: "" |
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|
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#### dynamic arith varname: assign |
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shopt -s parse_dynamic_arith # for LHS |
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|
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vec2_set () { |
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local this=$1 x=$2 y=$3 |
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: $(( ${this}_x = $2 )) |
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: $(( ${this}_y = y )) |
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} |
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vec2_set a 3 4 |
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vec2_set b 5 12 |
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echo a_x=$a_x a_y=$a_y |
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echo b_x=$b_x b_y=$b_y |
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## STDOUT: |
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a_x=3 a_y=4 |
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b_x=5 b_y=12 |
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## END |
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|
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#### dynamic arith varname: read |
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shopt -s eval_unsafe_arith # for RHS |
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|
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vec2_load() { |
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local this=$1 |
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x=$(( ${this}_x )) |
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: $(( y = ${this}_y )) |
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} |
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a_x=12 a_y=34 |
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vec2_load a |
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echo x=$x y=$y |
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## STDOUT: |
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x=12 y=34 |
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## END |
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|
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#### dynamic arith varname: copy/add |
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shopt -s parse_dynamic_arith # for LHS |
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shopt -s eval_unsafe_arith # for RHS |
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|
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vec2_copy () { |
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local this=$1 rhs=$2 |
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: $(( ${this}_x = $(( ${rhs}_x )) )) |
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: $(( ${this}_y = ${rhs}_y )) |
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} |
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vec2_add () { |
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local this=$1 rhs=$2 |
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: $(( ${this}_x += $(( ${rhs}_x )) )) |
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: $(( ${this}_y += ${rhs}_y )) |
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} |
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a_x=3 a_y=4 |
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b_x=4 b_y=20 |
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vec2_copy c a |
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echo c_x=$c_x c_y=$c_y |
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vec2_add c b |
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echo c_x=$c_x c_y=$c_y |
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## STDOUT: |
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c_x=3 c_y=4 |
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c_x=7 c_y=24 |
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## END |
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|
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#### is-array with ${var@a} |
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case $SH in (mksh|ash|dash|yash) exit 1 ;; esac |
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|
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function ble/is-array { [[ ${!1@a} == *a* ]]; } |
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|
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ble/is-array undef |
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echo undef $? |
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|
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string='' |
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ble/is-array string |
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echo string $? |
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|
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array=(one two three) |
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ble/is-array array |
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echo array $? |
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## STDOUT: |
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undef 1 |
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string 1 |
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array 0 |
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## END |
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## N-I zsh/mksh/ash/dash/yash status: 1 |
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## N-I zsh/mksh/ash/dash/yash stdout-json: "" |