cl_respawn: 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/cl_respawn - from package: heartbeat

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

On Debian possible default full paths are:

/usr/bin/cl_respawn - from package: heartbeat

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

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