dzfgrep: 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/dzfgrep - from package: debian-goodies

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

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