Month: August 2012

IT

Preupgrade – the root for the previously installed system was not found

Today, I've been digging through forums, log files and python scripts for about 16 hours (!!!) to update my system from Fedora 16 to Fedora 17. Apart from the fact that preupgrade for some reason downloaded all files from US mirrors (I'm in .nl), one of the biggest problems I had was the clear message "The root for the previously installed system was not found".

Why the fsck could it not find my installation? Was it the Luks full disk encryption? Or possibly the LVM volume manager? It couldn't be the btrfs filesystem, could it?

I tried everything possible, and when I was about to give up, I read this message that preupgrade has a problem with btrfs snapshots. Do I have these snapshots?

cryptsetup luksOpen /dev/sda2 disk
lvchange -ay vg_hdd/lv_root
mount /dev/mapper/vg_hdd-lv_root /mnt
btrfs subvolume list /mnt

There was the answer. I did. Two snapshots created by yum.

btrfs subvolume delete /mnt/yum-2012....1
btrfs subvolume delete /mnt/yum-2012....2
umount /mnt
lvchange -an vg_hdd/lv_root
cryptsetup luksClose disk

Damn, this has been a great day. Thanks to those crappy error messages. Time to go to bed.

© GeekLabInfo Preupgrade - the root for the previously installed system was not found is a post from GeekLab.info. You are free to copy materials from GeekLab.info, but you are required to link back to http://www.geeklab.info

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IT

Change the color of selected text

A nifty little detail in html5 is that you can change the color of selected text, which is usually blue. It's just one of those details that webdesigners usually forget.

You can change the color of the selection using the following css:

::selection {
    background-color: red;
    color: #fff;
}
::-moz-selection {
    background-color: red;
    color: #fff;
}

The ::selection is used by most modern browsers, except for Firefox. The latter uses its own selector ::-moz-selection. I read an article that wrote they cannot be combined. As such, the following will NOT work:

::selection, ::-moz-selection { /* You can't combine like this */
    background-color: red;
    color: #fff;
}
© GeekLabInfo Change the color of selected text is a post from GeekLab.info. You are free to copy materials from GeekLab.info, but you are required to link back to http://www.geeklab.info

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IT

Windows 7: Using symbolic links

Linux and unix have had this nifty little feature called symlinks (symbolic links) for decades. Windows has finally caught up with the new command mklink.

Windows Vista introduced the new command mklink, which was expanded in Windows 7.

Syntax

MKLINK [[/D] | [/H] | [/J]] Link Target
 
        /D      Creates a directory symbolic link.  Default is a file
                symbolic link.
        /H      Creates a hard link instead of a symbolic link.
        /J      Creates a Directory Junction.
        Link    specifies the new symbolic link name.
        Target  specifies the path (relative or absolute) that the new link
                refers to.

Examples

Link d:\myfile.txt (the file) to c:\something.txt (the link):

mklink c:\something.txt d:\myfile.txt

Make some crappy old program save its data to your fileserver directly by linking \\fileserver\data (target) to c:\program files\crappy-old-program\data (the directory).

mklink "c:\program files\crappy-old-program\data" \\fileserver\data /d
© GeekLabInfo Windows 7: Using symbolic links is a post from GeekLab.info. You are free to copy materials from GeekLab.info, but you are required to link back to http://www.geeklab.info

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