rpmls: 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/rpmls - from package: rpmdevtools

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

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