fox: 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/fox - from package: objcryst-fox

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

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