memcacheSync.php: 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/share/simplesamlphp/bin/memcacheSync.php - from package: simplesamlphp

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

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