certmaster-request: 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/certmaster-request - from package: certmaster

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

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