paw-gfortran: 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/paw-gfortran - from package: paw-gfortran

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

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