brightside: 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/brightside - from package: brightside

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

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