max_diskspace_used: 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/lib/plainbox-providers-1/checkbox/bin/max_diskspace_used - from package: plainbox-provider-checkbox

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

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