sooperlooper: 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/sooperlooper - from package: sooperlooper

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

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