Intermediate Linux / Unix System Administrator Tutorials

These tutorials assumes that you have strong understanding of Unix like operating systems and very comfortable with most aspects of the Unix/Linux operating system. Familiar with fundamental networking/distributed computing environments is required. ( rss feed )

I have over 1800+ pending comments and most of them are spams in WordPress based blog. How do I delete all (mass delete) the pending comments using sql statements?

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I am running Red Hat Enterprise Linux on IBM based system. How do I display bandwidth usage on an interface by host in real time using command line option? How do I monitor bandwidth usage in a real time on RHEL or CentOS Linux based server? How can I install iftop utility on CentOS or RHEL server using the yum command?

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I am a new Ubuntu Linux version 12.04 LTS user. How do I stop or start iptables based firewall service on Ubuntu Linux using bash command line options?

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How do I create and setup an OpenSSH config file to create shortcuts for servers I frequently access under Linux or Unix desktop operating systems?

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I need to set and test my web-app using Google cloud compute engine. How do I connect to an Instance Using ssh on Ubuntu Linux or Apple OS X based system?

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I am a new nginx user and I would like to redirect all mobile / smart phone users from www.example.com to m.example.com domain. How do I detect a mobile phone browser in nginx? How do I redirect all mobile users to sub-domain using regex based rules? How can I automatically redirects visitors on mobile devices to its mobile version at http://m.example.com/ and also allow mobile devices to the desktop website at www.example.com if visiting via http://www.example.com/?desktop=true?

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I am trying to set exec-shield protection on Linux as described here but getting the following error on Ubuntu Linux server version 12.04 LTS:

sysctl -w kernel.exec-shield=1
error: “kernel.exec-shield” is an unknown key

How do I fix this problem and make sure exec-shield buffer overflow protection security feature turned on Ubuntu Linux?

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