sbuild-adduser: 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/sbin/sbuild-adduser - from package: sbuild

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

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