nntpgrab_gui_qt: 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/nntpgrab_gui_qt - from package: nntpgrab-gui-qt

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

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