bnfc: 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/bnfc - from package: bnfc

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

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