whisper-update: 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/whisper-update - from package: python-whisper

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

On Debian possible default full paths are:

/usr/bin/whisper-update - from package: python-whisper

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

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