rpmsoname: 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/rpmsoname - from package: rpmdevtools

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

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