nmudiff: 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 Debian possible default full paths are:

/usr/bin/nmudiff - from package: devscripts

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

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