xrdp-dis: 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 CentOS possible default full paths are:

/usr/bin/xrdp-dis - from package: xrdp

You may install the required package with command yum install {package}

On Debian possible default full paths are:

/usr/bin/xrdp-dis - from package: xrdp

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

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