gnunet-resolver: 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/gnunet-resolver - from package: gnunet

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

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