koji-build-scratch: 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-build-scratch - from package: cmake-fedora

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

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