keepalived: 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/keepalived - from package: keepalived

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

On Debian possible default full paths are:

/usr/sbin/keepalived - from package: keepalived

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

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