otp: 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 CentOS possible default full paths are:

/usr/bin/otp - from package: heimdal-workstation

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/otp - from package: heimdal-clients
/usr/bin/otp - from package: otp

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

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