rpmdev-sha1: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH

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-sha1 - from package: rpmdevtools

You may install the required package with command yum install {package}
Error in other languages:
rpmdev-sha1: bevel nie gevind nie
rpmdev-sha1: comandă negăsită
rpmdev-sha1: comando não encontrado
rpmdev-sha1: commande introuvable
rpmdev-sha1: command not found
rpmdev-sha1: käsku ei ole
rpmdev-sha1: không tìm thấy lệnh
rpmdev-sha1: komanda nerasta
rpmdev-sha1: Kommando nicht gefunden.
rpmdev-sha1: kommandot finns inte
rpmdev-sha1: komut yok
rpmdev-sha1: nie znaleziono polecenia
rpmdev-sha1: níor aimsíodh an t-ordú
rpmdev-sha1: no se encontró la orden
rpmdev-sha1: no s'ha trobat l'ordre
rpmdev-sha1: opdracht niet gevonden
rpmdev-sha1: parancs nem található
rpmdev-sha1: perintah tidak ditemukan
rpmdev-sha1: príkaz nenájdený
rpmdev-sha1: příkaz nenalezen
rpmdev-sha1: команда не найдена
rpmdev-sha1: командата не е открита
rpmdev-sha1: 命令找不到
rpmdev-sha1: コマンドが見つかりません