whisper-info: 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-info - 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-info - from package: python-whisper

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

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