unxrandr: 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/unxrandr - from package: arandr

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

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