oxygen-shadow-demo: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH

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/oxygen-shadow-demo - from package: kde-workspace-bin

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