ztee: 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/sbin/ztee - from package: zmap

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

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