dfu-programmer: 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/dfu-programmer - from package: dfu-programmer

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

On Debian possible default full paths are:

/usr/bin/dfu-programmer - from package: dfu-programmer

You may install the required package with command apt-get install {package}

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