gencert: 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/gencert - from package: mod_nss

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

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