rahash2: 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/rahash2 - from package: radare2

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

Error in other languages:
rahash2: bevel nie gevind nie
rahash2: comandă negăsită
rahash2: comando não encontrado
rahash2: commande introuvable
rahash2: command not found
rahash2: käsku ei ole
rahash2: không tìm thấy lệnh
rahash2: komanda nerasta
rahash2: Kommando nicht gefunden.
rahash2: kommandot finns inte
rahash2: komut yok
rahash2: nie znaleziono polecenia
rahash2: níor aimsíodh an t-ordú
rahash2: no se encontró la orden
rahash2: no s'ha trobat l'ordre
rahash2: opdracht niet gevonden
rahash2: parancs nem található
rahash2: perintah tidak ditemukan
rahash2: príkaz nenájdený
rahash2: příkaz nenalezen
rahash2: команда не найдена
rahash2: командата не е открита
rahash2: 命令找不到
rahash2: コマンドが見つかりません