simplify: 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/simplify - from package: sanitizer

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

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