I have faced an issue while building an rpm in a CentOS machine. The error was rpm: /usr/bin/rpmspec: No such file or directory. To fix this issue we need to install the following package and re-run the build.
For CentOS 7 or RHEL 7 users
> sudo yum install rpm-build
For CentOS 8 or RHEL 8 users
> sudo dnf install rpm-build