nfpcapd: 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/nfpcapd - from package: nfdump

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

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