byobu-disable: 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/bin/byobu-disable - from package: byobu

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

On Debian possible default full paths are:

/usr/bin/byobu-disable - from package: byobu

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

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