Enterprise Linux: Auto sign custom RPM package with GPG key

[root@linux64-rpm-build-server ~]# yum install expect.x86_64

[buildmaster@linux64-rpm-build-server ~]$ cat ~/.rpmmacros
%_topdir %(echo $HOME)/rpmbuild
%_signature gpg
%_gpg_name Build Master

[buildmaster@linux64-rpm-build-server ~]$ cat /tmp/rpm-sign.exp
#!/usr/bin/expect -f

### rpm-sign.exp -- Sign RPMs by sending the passphrase.

spawn rpm --addsign {*}$argv
expect -exact "Enter pass phrase: "
send -- "<your_gpg_secret_key>\r"
expect eof

## end of rpm-sign.exp

[buildmaster@linux64-rpm-build-server ~]$ /tmp/rpm-sign.exp /<full_path_to_the_custom_RPM_package>