libde265-dec265: 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/libde265-dec265 - from package: libde265-examples

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

Error in other languages:
libde265-dec265: bevel nie gevind nie
libde265-dec265: comandă negăsită
libde265-dec265: comando não encontrado
libde265-dec265: commande introuvable
libde265-dec265: command not found
libde265-dec265: käsku ei ole
libde265-dec265: không tìm thấy lệnh
libde265-dec265: komanda nerasta
libde265-dec265: Kommando nicht gefunden.
libde265-dec265: kommandot finns inte
libde265-dec265: komut yok
libde265-dec265: nie znaleziono polecenia
libde265-dec265: níor aimsíodh an t-ordú
libde265-dec265: no se encontró la orden
libde265-dec265: no s'ha trobat l'ordre
libde265-dec265: opdracht niet gevonden
libde265-dec265: parancs nem található
libde265-dec265: perintah tidak ditemukan
libde265-dec265: príkaz nenájdený
libde265-dec265: příkaz nenalezen
libde265-dec265: команда не найдена
libde265-dec265: командата не е открита
libde265-dec265: 命令找不到
libde265-dec265: コマンドが見つかりません