sbuild-unhold: 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/sbuild-unhold - from package: sbuild

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

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