arm-koji: 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/arm-koji - from package: fedora-packager

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

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