Category Archives: Hints and Tips

Flush DNS cache on MacOS

For most versions of OSX and macOS I have found the following works sudo killall -HUP mDNSResponder I have seen notes to indicate that  dnscacheutil -flushcache  or discoveryutil udnsflushcaches are needed for  Yosemite and older versions. Thanks to: https://help.dreamhost.com/hc/en-us/articles/214981288-Flushing-your-DNS-cache-in-Mac-OS-X-and-Linux amongst other sites.

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Ubuntu Removing unwanted kernels

If you have ever struggled with Ubuntu Server and the /boot/partition being filled up as a result of ‘apt upgrades’ then I’m with you.  For me until recently the process I use is as follows: sudo apt updatesudo apt autoremovesudo apt upgrade -y … Continue reading

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mod_rewrite in .htaccess

In the process of migrating the website I needed to catch old URLs and map them to the locations of the documents on the new website. Deploy a .htaccess file in the root of the website and introduce Redirect 301’s. Simples… Well … Continue reading

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Python MatPlotLib on MacOS

To accompany NumPy and PyLab we need a way of producing graphical output and the prefered route is MatPlotLib. The problem is that the ‘out of the box‘ pip installation on MacOS creates a slightly unfriendly configuration which means graphs don’t display without a ‘.show()’ command and then they’re … Continue reading

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OpenVPN 2.2.x and iOS 9.3.x – No routing over the VPN

Whilst going through the process of renewing certificates, and the recent updates for OpenVPN and iOS, I discovered that traffic was no longer being routed over the tunnel. There are a number of postings blaming changes that Apple have made … Continue reading

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SSH Escape Commands

These are the ssh escape commands from within an ssh connected session. %~? Supported escape sequences: ~.  – terminate connection (and any multiplexed sessions)  ~B  – send a BREAK to the remote system  ~C  – open a command line  ~R  – Request rekey (SSH protocol … Continue reading

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