vm: 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/vm - from package: mgetty-voice

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

On Debian possible default full paths are:

/usr/bin/vm - from package: mgetty-voice

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

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