alt-key: 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/alt-key - from package: alt-key

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

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