gpaw: 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/gpaw - from package: gpaw

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

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