debsign: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH

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/debsign - from package: devscripts

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