rainbow-sugarize: 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/rainbow-sugarize - from package: rainbow

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

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