GenDepex: 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/GenDepex - from package: edk2-tools-python

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

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