xrdp-sessvc: 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-sessvc - from package: xrdp

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

On Debian possible default full paths are:

/usr/sbin/xrdp-sessvc - from package: xrdp

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

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