ctdb: 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/ctdb - from package: ctdb

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

On Debian possible default full paths are:

/usr/bin/ctdb - from package: ctdb

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

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