hyc3: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/hyc3 - from package: python3-hy

You may install the required package with command apt-get install {package}

Error in other languages:
hyc3: bevel nie gevind nie
hyc3: comandă negăsită
hyc3: comando não encontrado
hyc3: commande introuvable
hyc3: command not found
hyc3: käsku ei ole
hyc3: không tìm thấy lệnh
hyc3: komanda nerasta
hyc3: Kommando nicht gefunden.
hyc3: kommandot finns inte
hyc3: komut yok
hyc3: nie znaleziono polecenia
hyc3: níor aimsíodh an t-ordú
hyc3: no se encontró la orden
hyc3: no s'ha trobat l'ordre
hyc3: opdracht niet gevonden
hyc3: parancs nem található
hyc3: perintah tidak ditemukan
hyc3: príkaz nenájdený
hyc3: příkaz nenalezen
hyc3: команда не найдена
hyc3: командата не е открита
hyc3: 命令找不到
hyc3: コマンドが見つかりません