grep-debtags: 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/grep-debtags - from package: dctrl-tools

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

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