byobu: 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 - from package: byobu

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

On Debian possible default full paths are:

/usr/bin/byobu - from package: byobu

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

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