dep3changelog: 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/dep3changelog - from package: devscripts

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

Error in other languages:
dep3changelog: bevel nie gevind nie
dep3changelog: comandă negăsită
dep3changelog: comando não encontrado
dep3changelog: commande introuvable
dep3changelog: command not found
dep3changelog: käsku ei ole
dep3changelog: không tìm thấy lệnh
dep3changelog: komanda nerasta
dep3changelog: Kommando nicht gefunden.
dep3changelog: kommandot finns inte
dep3changelog: komut yok
dep3changelog: nie znaleziono polecenia
dep3changelog: níor aimsíodh an t-ordú
dep3changelog: no se encontró la orden
dep3changelog: no s'ha trobat l'ordre
dep3changelog: opdracht niet gevonden
dep3changelog: parancs nem található
dep3changelog: perintah tidak ditemukan
dep3changelog: príkaz nenájdený
dep3changelog: příkaz nenalezen
dep3changelog: команда не найдена
dep3changelog: командата не е открита
dep3changelog: 命令找不到
dep3changelog: コマンドが見つかりません