degrep: 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/degrep - from package: debian-goodies

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

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