koji-containerbuild: 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/koji-containerbuild - from package: koji-containerbuild-cli

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

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