liveusb-creator: 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/sbin/liveusb-creator - from package: liveusb-creator

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

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