zdb: 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/zdb - from package: zfs-fuse

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

On Debian possible default full paths are:

/sbin/zdb - from package: zfs-fuse

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

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