xm_info_free_memory: 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/sbin/xm_info_free_memory - from package: dtc-xen

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

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