beer: 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 Debian possible default full paths are:

/usr/bin/beer - from package: gerstensaft

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

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