unzoo: 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 CentOS possible default full paths are:

/usr/bin/unzoo - from package: unzoo

You may install the required package with command yum install {package}

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