addhost: 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/addhost - from package: dmucs

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

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