xrdp: 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/sbin/xrdp - from package: xrdp

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

On Debian possible default full paths are:

/usr/sbin/xrdp - from package: xrdp

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

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