alt-ergo: 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-ergo - from package: alt-ergo

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

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