rpmdev-newinit: 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/rpmdev-newinit - from package: rpmdevtools

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

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