If you ever want to build and RPM, you need to make sure that the things it requires are installed. These are listed in the SPEC file on lines that begin with BuildRequires.  Installing these by hand is time consuming enough that it should be automated.  Here’s a first hack in Python.

#!/usr/bin/python
import sys
import re

build_re = re.compile('BuildRequires:.*')
compare_re = re.compile('.*=.*')


def main():
    if (len(sys.argv) > 1):
        spec = open(sys.argv[1])
        for line in spec:
            if build_re.match(line):
                for token in line.rsplit(" "):
                    if build_re.match(token):
                        continue
                    if compare_re.match(token):
                        break
                    token = token.rstrip(" ,\n\r")
                    if len(token) > 0:
                        print token


if __name__ == "__main__":
    main()

To use it, save in a file called buildreqs.py and run:

sudo yum install `./buidreqs.py ~/rpmbuild/SPECS/krb5.spec`