sass: 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/sass - from package: ruby-sass

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

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