rax2: 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/rax2 - from package: radare2

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

Error in other languages:
rax2: bevel nie gevind nie
rax2: comandă negăsită
rax2: comando não encontrado
rax2: commande introuvable
rax2: command not found
rax2: käsku ei ole
rax2: không tìm thấy lệnh
rax2: komanda nerasta
rax2: Kommando nicht gefunden.
rax2: kommandot finns inte
rax2: komut yok
rax2: nie znaleziono polecenia
rax2: níor aimsíodh an t-ordú
rax2: no se encontró la orden
rax2: no s'ha trobat l'ordre
rax2: opdracht niet gevonden
rax2: parancs nem található
rax2: perintah tidak ditemukan
rax2: príkaz nenájdený
rax2: příkaz nenalezen
rax2: команда не найдена
rax2: командата не е открита
rax2: 命令找不到
rax2: コマンドが見つかりません