otpw-gen: 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/otpw-gen - from package: otpw-bin

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

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