environment assignment

envtest

#!/usr/bin/env bash

unset -v x y sh

while IFS= read -r s; do
    IFS= declare -a "shells=( $s )"
    IFS= read -r testCase
    printf '%s\n%6s%s\n' "$testCase" '' 'x y x y'
    for sh in "${shells[@]}"; do
        printf '%-4s: %s\n' "$sh" "$("$sh" -c "$testCase")"
    done
    echo
done <<"EOF"
sh {{b,d}a,po,{,m}k,z}sh bb
x= y=${x:=1} sh -c 'printf "%1s %1s" "$x" "$y"'; printf ' %1s %1s' "$x" "$y"
sh {{b,d}a,po,{,m}k,z}sh bb
x=2 y=2; x= y=${x:=1} sh -c 'printf "%1s %1s" "$x" "$y"'; printf ' %1s %1s' "$x" "$y"
sh {{b,d}a,po,{,m}k,z}sh bb
y=${x:=1} sh -c 'printf "%1s %1s" "$x" "$y"'; printf ' %1s %1s' "$x" "$y"
sh {{b,d}a,po,{,m}k,z}sh bb
x=2 y=2; x=1 y=$x sh -c 'printf "%1s %1s" "$x" "$y"'; printf ' %1s %1s' "$x" "$y"
sh {{b,d}a,po,{,m}k,z}sh bb
x= y=${x:=1} eval 'printf %1s\ %1s "$x" "$y"'; printf ' %1s %1s' "$x" "$y"
sh {{b,d}a,po,{,m}k,z}sh bb
[ -n "${ZSH_VERSION+_}" ] && setopt -o POSIX_BUILTINS; f() { printf '%1s %1s' "$x" "$y"; }; x=2 y=2; x=1 y= command eval 'y=$x f'; printf ' %1s %1s' "$x" "$y"
{{,m}k,z}sh
[ -n "${ZSH_VERSION+_}" ] && setopt -o POSIX_BUILTINS; function f { printf '%1s %1s' "$x" "$y"; }; x=2 y=2; x=1 y= command eval 'y=$x f'; printf ' %1s %1s' "$x" "$y"
{,m}ksh
function f { printf '%1s %1s' "$x" "$y"; }; x=2 y=2; x= y=${x:=1} f; printf ' %1s %1s' "$x" "$y"
{,m}ksh
f() { printf '%1s %1s' "$x" "$y"; }; x=2 y=2; x= y=${x:=1} f; printf ' %1s %1s' "$x" "$y"
EOF

# vim: set fenc=utf-8 ff=unix ts=4 sts=4 sw=4 ft=sh nowrap et:

out

x= y=${x:=1} sh -c 'printf "%1s %1s" "$x" "$y"'; printf ' %1s %1s' "$x" "$y"
      x y x y
sh  : 1 1 1  
bash: 1 1 1  
dash:   1    
posh: 1 1    
ksh : 1 1    
mksh:   1 1  
zsh : 1 1    
bb  :     1  

x=2 y=2; x= y=${x:=1} sh -c 'printf "%1s %1s" "$x" "$y"'; printf ' %1s %1s' "$x" "$y"
      x y x y
sh  : 1 1 1 2
bash: 1 1 1 2
dash:   1 2 2
posh: 1 1 2 2
ksh : 1 1 2 2
mksh:   2 2 2
zsh : 1 1 2 2
bb  :     1 2

y=${x:=1} sh -c 'printf "%1s %1s" "$x" "$y"'; printf ' %1s %1s' "$x" "$y"
      x y x y
sh  :   1 1  
bash:   1 1  
dash:   1 1  
posh:   1 1  
ksh :   1 1  
mksh:   1 1  
zsh :   1    
bb  :   1 1  

x=2 y=2; x=1 y=$x sh -c 'printf "%1s %1s" "$x" "$y"'; printf ' %1s %1s' "$x" "$y"
      x y x y
sh  : 1 1 2 2
bash: 1 1 2 2
dash: 1 1 2 2
posh: 1 1 2 2
ksh : 1 1 2 2
mksh: 1 2 2 2
zsh : 1 1 2 2
bb  : 1 1 2 2

x= y=${x:=1} eval 'printf %1s\ %1s "$x" "$y"'; printf ' %1s %1s' "$x" "$y"
      x y x y
sh  : 1 1 1 1
bash: 1 1 1  
dash: 1 1 1 1
posh: 1 1 1 1
ksh : 1 1 1 1
mksh: 1 1 1 1
zsh : 1 1    
bb  :        

[ -n "${ZSH_VERSION+_}" ] && setopt -o POSIX_BUILTINS; f() { printf '%1s %1s' "$x" "$y"; }; x=2 y=2; x=1 y= command eval 'y=$x f'; printf ' %1s %1s' "$x" "$y"
      x y x y
sh  : 1 1 2 2
bash: 1 1 2 2
dash: 1 1 2 2
posh: 1 1 2 2
ksh : 1 1 2 2
mksh: 1 1 2 2
zsh : 1 1 1 1
bb  : 2 2 2 2

[ -n "${ZSH_VERSION+_}" ] && setopt -o POSIX_BUILTINS; function f { printf '%1s %1s' "$x" "$y"; }; x=2 y=2; x=1 y= command eval 'y=$x f'; printf ' %1s %1s' "$x" "$y"
      x y x y
ksh : 1 1 2 2
mksh: 1 1 2 2
zsh : 1 1 1 1

function f { printf '%1s %1s' "$x" "$y"; }; x=2 y=2; x= y=${x:=1} f; printf ' %1s %1s' "$x" "$y"
      x y x y
ksh : 1 1 2 2
mksh:   2 2 2

f() { printf '%1s %1s' "$x" "$y"; }; x=2 y=2; x= y=${x:=1} f; printf ' %1s %1s' "$x" "$y"
      x y x y
ksh : 1 1 1 1
mksh: 1 1 1 1