zoo: 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/zoo - from package: zoo

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

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