byobu-ugraph: 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-ugraph - from package: byobu

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

On Debian possible default full paths are:

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

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

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