rpminfo: 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/rpminfo - from package: rpmdevtools

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

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