a=$'a\001b'

e=$'uv\001\001wx'

recho $a
recho $e

recho ${a/$'\001'/A}
recho "${a/$'\001'/A}"
recho ${e/$'\001'/A}
recho "${e/$'\001'/A}"

recho ${a/b/B}
recho "${a/b/B}"
recho ${e/w/W}
recho "${e/w/W}"

recho ${a//$'\001'/A}
recho "${a//$'\001'/A}"
recho ${e//$'\001'/A}
recho "${e//$'\001'/A}"

recho ${a//b/B}
recho "${a//b/B}"
recho ${e//w/W}
recho "${e//w/W}"

# pos params pat subst

set $e $e

recho ${@/$'\001'/A}
recho "${@/$'\001'/A}"
recho ${@/w/W}
recho "${@/w/W}"

recho ${@//$'\001'/A}
recho "${@//$'\001'/A}"
recho ${@//w/W}
recho "${@//w/W}"

arr[0]=$a
arr[1]=$e

recho ${arr[0]}
recho ${arr[1]}

recho ${arr[0]/$'\001'/A}
recho "${arr[0]/$'\001'/A}"
recho ${arr[1]/$'\001'/A}
recho "${arr[1]/$'\001'/A}"

recho ${arr[0]/b/B}
recho "${arr[0]/b/B}"
recho ${arr[1]/w/W}
recho "${arr[1]/w/W}"

recho ${arr[0]//$'\001'/A}
recho "${arr[0]//$'\001'/A}"
recho ${arr[1]//$'\001'/A}
recho "${arr[1]//$'\001'/A}"

recho ${arr[0]//b/B}
recho "${arr[0]//b/B}"
recho ${arr[1]//w/W}
recho "${arr[1]//w/W}"

recho ${arr[@]/$'\001'/A}
recho "${arr[@]/$'\001'/A}"

recho ${arr[@]/b/B}
recho "${arr[@]/b/B}"
recho ${arr[@]/w/W}
recho "${arr[@]/w/W}"

recho ${arr[@]//$'\001'/A}
recho "${arr[@]//$'\001'/A}"

recho ${arr[@]//b/B}
recho "${arr[@]//b/B}"
recho ${arr[@]//w/W}
recho "${arr[@]//w/W}"