For 2023 - we are now fully retired from IT training. We have made many, many friends over 25 years of teaching about Python, Tcl, Perl, PHP, Lua, Java, C and C++ - and MySQL, Linux and Solaris/SunOS too. Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own risk.
Lisa and I (Graham) now live in what was our training centre in Melksham - happy to meet with former delegates here - but do check ahead before coming round. We are far from inactive - rather, enjoying the times that we are retired but still healthy enough in mind and body to be active!
I am also active in many other area and still look after a lot of web sites - you can find an index ((here)) |
Slow boot and terminal start on Linux boxes
Now this was a mystery. I had two Linux boxes which booted perfectly when used inhouse, but very slowly indeed (10 minutes plus) when in use on a customer site. Very awkward really - we would test out the systems in Melksham and find them fine, but then they would fail in Bristol. Even calling up a terminal window took minutes!
A clue ... with pauses at networking, sendmail and sm-client ... the problem had to be DNS (domain name service) related, but I checked all the systems - good and bad - and found the same name servers in /etc/resolv.conf and the same host line in /etc/nsswitch.conf, namely
hosts files dns
It turns out that the problem is in /etc/hosts. My machines have names like holt.wellho.net, trowbridge.wellho.net, iford.wellho.net and easterton.wellho.net and if the /etc/hosts file contained both the short (trowbridge) and long (trowbridge.wellho.net) names against 127.0.0.1, it worked fine - but if the fully qualified name was missing it was going to DNS and failing to find it away from the office.
Isn't it gauling how - once you have spend what seems like an eternity trackinging something like this down - the final answer is so darned obvious! (written 2008-06-05)
Associated topics are indexed as below, or enter http://melksh.am/nnnn for individual articles A171 - Web Application Deployment - Linux Server Admin - Exercise [1719] A special day - last Friday in July - (2008-07-25) [2491] Root is root for a reason! - (2009-11-03) A163 - Web Application Deployment - Network Configuration and Security [11] A bolt of lightning on Multicasting - (2004-08-11) [37] Security and Safety - (2004-09-03) [267] Searching security holes - (2005-04-04) [332] Looking up IP addresses - (2005-06-01) [506] What are DHCP and DNS? - (2005-11-27) [511] Domain Forwarding - 2 ways of doing it - (2005-11-29) [1073] Heartbeat script in Perl - (2007-02-09) [1408] Wireless hotel tips - FTP and Skype connections failing - (2007-10-26) [1712] As different as night and tyres - (2008-07-18) [1904] Ruby, Perl, Linux, MySQL - some training notes - (2008-11-23) [2052] How was my web site compromised? - (2009-02-24) [2489] Parallel Pinging, using Python Threads or Expect spawn lists - (2009-11-02) [3448] Checking all the systems on a subnet, using Expect and Tk - (2011-09-18) [4134] Setting up your MacBook Air as a mobile broadband router - (2013-07-07)
Some other Articles
Dynamic Memory Allocation in CWhat are Unions (C programming)Talk on TransWilts train service to Green PartyChecking server performance for PHP generated pagesSlow boot and terminal start on Linux boxesFactory method example - PerlExample of OO in PerlPython in an afternoon - a lecture for experienced programmersWestonbirt Arboretum PostcodeEquality, sameness and identity - Python
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This is a page archived from The Horse's Mouth at
http://www.wellho.net/horse/ -
the diary and writings of Graham Ellis.
Every attempt was made to provide current information at the time the
page was written, but things do move forward in our business - new software
releases, price changes, new techniques. Please check back via
our main site for current courses,
prices, versions, etc - any mention of a price in "The Horse's Mouth"
cannot be taken as an offer to supply at that price.
Link to Ezine home page (for reading).
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