clush: 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/clush - from package: clustershell

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

On Debian possible default full paths are:

/usr/bin/clush - from package: clustershell

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

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