Autarchy of the Private Cave

Tiny bits of bioinformatics, [web-]programming etc

    How to: convert your VPS root filesystem to btrfs (using rescue boot)

    15th February 2016

    I’m moving from (a kind of…) a dedicated server to a VPS, to decrease my frightful anticipation of hardware failures.
    Honestly though, that server had been freezing up and restarting spontaneously for several months now, causing sometimes really long down-times…
    That server is now about 6-7 years old, built with off-the-shelf components, some of which (the HDD :) ) had weird noises from the very start.
    Definitely time to move!

    I’ve purchased a fairly cheap VPS with an easy, one-click upgrade option for after I’m done configuring it.
    It comes with a wide selection of OSes to pre-install; I’ve chosen Debian Jessie, version 8.3 as of this writing.

    I wanted to use btrfs from the beginning, so could have installed Debian myself, but… VPS provider does some initial configuration (like their Debian mirror and some other things), so I’ve felt that converting to btrfs after the fact would be easier. Now that I’ve done this – I guess it was fairly easy, although preparation did take some time.

    Below, I’m providing step-by-step instructions on how to convert your root filesystem from (most likely) ext4 to btrfs.
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    Posted in *nix, how-to | No Comments »

    Email address to image converter

    21st April 2009

    After trying several of the kind, I found CHXO email address to image converter a reliable and working one.
    It supports transparent PNGs, and just works. Also, it comes with a complete PHP source, so it looks like you can embed it into your own web-applications. (As it is GPLed, I’ve saved a copy for myself.)

    For Gmailers, there’s a nicer generator.

    If you’d like to convert larger amounts of text to images, then use hidetext.net:
    hidetext.net

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    Posted in Links, Software, Web | No Comments »

    Convert MySQL database from one encoding/collation into another

    8th February 2008

    Most frequent use: convert database from latin1_swedish to utf8_general_ci.
    Original script found at: MySQL and UTF-8.

    Update: the original script had an error, it would generate queries likes this one (note the bold part):

    ALTER TABLE `links` CHANGE `link_rel` `link_rel` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL DEFAULT NULL;

    This is clearly wrong syntax (and logic). I fixed this by making comparison to NULL strict (with three equal signs instead of two):

    // Does the field default to null, a string, or nothing?
    if ($row['Default'] === NULL)

    Update 2: based on comment by banesto, I modified the script; now it does not require specifying the from_collation, it’s sufficient to specify to_collation (which will be used for all the fields and tables). The modified code is:

    if ($row['Collation'] == ” || $row['Collation'] == $convert_to)
    continue;

    Update 3: the long-lasting, re-appearing NOT NULL DEFAULT NULL problem is finally fixed.

    Update 4: incorporated Russ’s fix to skip numeric fields (in order to leave autoincrement values intact).

    Here’s the script itself: (to copy-paste: first click the “Plain text” header)
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    Posted in Links, Notepad, PHP, Programming, Web | 59 Comments »