pvffilter: 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/pvffilter - from package: mgetty-voice

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

On Debian possible default full paths are:

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

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

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