rxstack: 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/bin/rxstack - from package: regina-rexx

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

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