pvffft: 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/pvffft - from package: mgetty-voice

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

On Debian possible default full paths are:

/usr/bin/pvffft - from package: mgetty-pvftools

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

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