docker-pi-hole/src/s6/debian-root/usr/bin/set-contenv

#!/usr/bin/execlineb -S0

if { s6-test $# -eq 2 }

backtick -in FILENAME {
    pipeline { s6-echo "${1}" }
    tr "a-z" "A-Z"
}
import -u FILENAME

redirfd -w 1 /var/run/s6/container_environment/${FILENAME}
s6-echo -n -- ${2}