grep-excuses: 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-excuses - from package: devscripts

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

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