case of a failed Ambari agent install, error "/var/tmp/rpm-tmp.vEw9Wk: line 31: /var/lib/ambari-agent/install-helper.sh: Permission denied"
I was struggling with an issue installing Ambari agent on a few servers. These servers were not any different than any other servers except that they were running master services. When I would try to install an agent I'd get "/var/tmp/rpm-tmp.vEw9Wk: line 31: /var/lib/ambari-agent/install-helper.sh: Permission denied". It would still install but some libraries missing. If I'd try to start an agent I'd get "/usr/sbin/ambari-agent: line 59: /var/lib/ambari-agent/ambari-sudo.sh: Permission denied ". My sleuthing led to me discover that /usr/lib/python2.6/site-packages/ambari_agent did not have enough files as other servers, python script would throw "ImportError: No module named ambari_commons.exceptions". So I copied the library from a different server, yada yada. I failed miserably at everything I tried, it was not a file permissions or SELinux issue. Then I worked with a Hortonworks engineer who realized that within /var/lib/ambari-agent directory, he can't even tab complete. So he looked at /etc/fstab and what we realized is that /var was mounted with noexec. As soon as the noexec switch was removed, ambari-agent reinstalled and restarted successfully.