version: 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/lib/mailman/bin/version - from package: mailman

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

On Debian possible default full paths are:

/usr/lib/mailman/bin/version - from package: mailman

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

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