Technology Tales

Restoring the MBR for Windows 7

During my explorations of dual-booting of Windows 7 and Ubuntu 10.10, I ended up restoring the master boot record (MBR) so that Windows 7 could load again or to find out if it wouldn't start for me. The first hint that came to me when I went searching was the bootsect command, but this only updates the master boot code on the partition, so it did nothing for me. What got things going again was the bootrec command.

To use either of these, I needed to boot from a Windows 7 installation DVD. With my Toshiba Equium laptop, I needed to hold down the F12 key until I was presented with a menu that allowed me to choose from what drive I wanted to boot the machine, the DVD drive in this case. Then, the disk started and gave me a screen where I selected my location and moved to the next one where I selected the Repair option. After that, I got a screen where my Windows 7 installation was located. Once that was selected, I moved on to another screen from I started a command line session. Then, I could issue the commands that I needed.

bootsect /nt60 C:

This would repair the boot sector on the C: drive in a way that is compatible with BOOTMGR. Though this wasn't enough for me, it was something worth trying anyway in case there was some corruption.

bootrec /fixmbr
bootrec /fixboot

The first of these restores the MBR, and the second sorts out the boot sector on the system drive (where the Windows directory resides on your system). In the event, I ran both of these and Windows restarted again, proving that it had come through disk partition changes without a glitch, though CHKDISK did run in the process, but that's understandable. There's another option for those wanting to get back their boot menu, and here it is:

bootrec /rebuildbcd

Though I didn't need to do so, I ran that too, but later used EasyBCD to remove the boot menu from the start-up process because it was surplus to my requirements. That's a graphical tool that has gained something of a reputation since Microsoft dispensed with the boot.ini file that came with Windows XP for later versions of the operating system.

Using Data Step to Create a Dataset Template from a Dataset in SAS

Recently, I wanted to make sure that some temporary datasets that were being created during data processing in a dataset creation program weren't truncating values or differed from the variable lengths in the original. It was then that a brainwave struck me: create an empty dataset shell using data step, and use that set all the variable lengths for me when the new datasets were concatenated to it. The code turned out to be very simple and here is an example of how it looked:

data shell;
    stop;
    set example;
run;

The STOP statement, prevents the data step from reading in any of the values in the template dataset and just its header is written out to another (empty) dataset that can be used to set things up as you would want them to be. It certainly was a quick solution in my case.

Manually adding an entry for Windows 7 to an Ubuntu GRUB2 menu

A recent endeavour of mine has been to set up a dual-booting arrangement on my Toshiba Equium laptop, with Ubuntu 10.10 and Windows 7 side by side on there. However, unlike the same attempt with my Asus Eee PC where Windows XP coexists with Ubuntu, there was no menu entry on the GRUB (I understand that Ubuntu has had version 2 of this since 9.04 though the internal version is of the form 1.9x; you can issue grub-install -v at the command line to find out what version you have on your system) menu afterwards. Thankfully, I eventually figured out how to do this and the process is shared here in a more coherent order than the one in which I discovered all the steps.

The first step is to edit /etc/grub.d/40_custom (using sudo) and add the following lines to the bottom of the file:

menuentry 'Windows 7' {
set root='(hd0,msdos2)'
chainloader +1
}

Since the location of the Windows installation can differ widely, I need to explain the "set root" line because (hd0,msdos2) refers to /dev/sda2 on my machine. More generally, hd0 (or /dev/sda elsewhere) refers to the first hard disk installed in any PC, with hd1 (or /dev/sdb elsewhere) being the second and so on. While I was expecting to see entries like (hd0,6) in /boot/grub/grub.cfg, what I saw were ones like (hd0,msdos6) instead with the number in the text after the comma being the partition identifier; 1 is the first (sda1), 2 (sda2) is the second and so on. The next line (staring with chainloader) tells GRUB to load the first sector of the Windows drive so that it can boot. After all that decoding, my final remark on what's above is a simple one: the text "Windows 7" is what will appear in the GRUB menu, so you can change this as you see fit.

After saving 40_custom, the next step is to issue the following command to update grub.cfg:

sudo update-grub2

Once that has done its business, then you can look into /boot/grub/grub.cfg to check that the text added into 40_custom has found its way in there. That is important because this is the file read by GRUB2 when it builds the menu that appears at start-up time. A system reboot will prove conclusively that the new entry has been added successfully. Then, there's the matter of selectively to see if Windows loads properly like it did for me, once I chose the correct disk partition for the menu entry, that is!

Changing the earpiece volume on a Nokia 1661

Since the Nokia 1661 is an entry-level phone, you'd have thought that they'd have made it obvious how to change the earpiece volume on the thing. However, it turns out to be something for which you do need to consult its manual, and it's not as user-friendly as it could be either. Seemingly, the earpiece volume only can be adjusted while you're already on a phone call: you need to use the scroll key (push in left and right sides as needed) that could be right up against your face at the time!

My way around this is to phone the speaking clock (123 in the U.K.) and adjust the earpiece while that call is in progress. Then, you're set for future conversations with real people. Well, anything's better than not being able to hear the other person due to background noise, and my Nokia 1661 came with its volume set rather too low for me if I recall correctly. While I can appreciate the need to look after your hearing, you do need to have coherent phone conversations too.

A cautionary tale regarding Excel spreadsheet sharing

Recently, I encountered a reason to be wary about creating shared Excel spreadsheets when one ballooned in size. It ended up growing to around 130 megabytes before I tried turning off sharing to see what happened and the size shrunk to under 200 kilobytes. From this, it would appear that the version control information was the cause of the explosion in file size.

With that in mind, I set about to looking through the settings to see if there were any that might need optimisation. While the default action is to keep thirty days of change tracking, I have this reduced to a single day in order not to be keeping too much. Quite how much, you need to retain is up to you, but I will be keeping an eye on things now that I have done this.

On upgrading from Fedora 13 to Fedora 14

My Fedora box recently got upgraded to the latest version of the distribution (14) and I stuck to a method that I have used successfully before and one that isn't that common with variants of Linux either. What I did was to go to the Fedora website and download a full DVD image, burn it to a disk and boot from that. Then, I chose the upgrade option from the menus and all went smoothly with only commonplace options needing selection from the menus and no data got lost either. Apparently, this way of going about things is only offered by the DVD option because the equivalent Live CD versions only do full installations.

However, there was another option that I fancied trying, but was stymied by messages about a troublesome Dropbox repository. As I later discovered, that would have been easily sorted, only for my opting for a tried and tested method instead. This was a pity because only two commands would have needed to be issued when logged in as root, and it would have been good to have had a go with them:

yum update yum
yum --releasever=14 update --skip-broken

These may have done what I habitually do with Ubuntu upgrades but trying them out either will have to await the release of the next version or my getting around to setting up a Fedora virtual machine to see what happens. The latter course of action might be sensible anyway to see if all works without any problems before doing it for a real PC installation.

Ridding Fedora of Unwanted Software Repositories

Like other Linux distributions, Fedora has the software repository scheme of things for software installation and updating. However, it could do with having the ability to remove unwanted repositories through a GUI, only it doesn't. What you need to do instead is switch to root in a terminal using the command su - and enter your root user password before navigating to /etc/yum.repos.d/ to delete the troublesome [file name].repo file. Recently, I needed to do this after upgrading to Fedora 14 or yum wouldn't work from the command line, which is the way that I tend to update Fedora (yum -y update is the command that I use because it automatically does all installations unattended until it is finished doing what's needed). The offending repository, or "Software Source" as these things are called in the GUI, belonged to Dropbox and even disabling it didn't make yum operate from the command like it should, so it had to go. Maybe Dropbox hasn't caught up with the latest release of Fedora, but that can be resolved another day.

Taking the sudo command beyond Ubuntu

Though some may call it introducing a security risk, being able to execute administrator commands on Ubuntu using sudo and gksu by default is handy. It's not the only Linux distribution with the facility, though, since the /etc/sudoers file is found in Debian and I plan to have a look into Fedora. The thing that needs to be done is to add the following line to the aforementioned file (you will need to do this as root):

[your user name] ALL=(ALL) ALL

One that is done, you are all set. Just make sure that you're using a secure password, though, and removing the sudo/gksu permissions is as simple as reversing the change.

Update on 2011-12-03: The very same can be done for both Arch Linux and Fedora, The same file locations apply too.

Turning off the admin bar in WordPress 3.1

Work on WordPress 3.1 is in full swing at the moment, though I initially thought that they were taking a little break after 3.0. From what I can see, many refinements are being made to the multi-blog functionality and behind-the-scenes work is ongoing on the administration screens too.

Another under-the-bonnet change has been to make WordPress less tied to MySQL, since the possibility of dropping in support for an alternative such as PostgreSQL is now a reality even if it isn't part of the default package. For now, it looks as if this will be plugin territory rather than default multi-database support, though that may become a sensible development in the light of Oracle's acquisition of MySQL and its sabre-rattling regarding Java patents. So far, the change to WordPress has affected my use of its database engine to power an offline version of my online photo gallery, but a quick spot of code editing sorted that issue.

One more obvious alteration will be the addition of a WordPress.com style administration bar to the top of all content and administration screens for a user who is logged into the system. Though it will be turned on by default, there will be the option of turning it off for those among who prefer things that way. All that will be needed for this is to add the following line near the top of wp-config.php:

define( "WP_SHOW_ADMIN_BAR", false);

The chance to see new additions like those above and be ready for is my main reason for following WordPress development. It's best to be ready instead of being surprised, though it has to be said that the blogging or CMS platform is a very polished one these days.

One reason why you cannot merge cells in Excel

One handy thing that I didn't realise that you could do with Excel until the last few months was the ability to share an open workbook between users and collate any changes that are made (it seems that a form of version control is behind this). From what I have seen, Excel seems to manage changes to shared spreadsheets rather well. When you save yours, it adds updates from other users and warns if any edits collide with one another. To activate it in Excel 2003, all that needs doing is for you to go to the Share Workbook entry on the Tools and tick the appropriate checkbox in the resulting dialogue box. In 2007 and 2010, look for the Share Workbook icon in the Review tab on the ribbon to get the same dialogue box popping up.

That's not to say that it doesn't have its restrictions, though. For example, I have found that the merging of cells is made unavailable, but that can be sorted by unsharing and resharing the workbook when no one else is using it. As to why cell merger is switched off by sharing, I have a few ideas. Maybe, they couldn't make it work reliably (can happen with large software development projects like the creation of a new version of Excel) or decided that it would have consequences for other users that are too inconvenient. Either way, we cannot merge cells in shared workbooks, and that's the way that things are for now. Some may not worry about this though, since they reckon that cell merging is undesirable anyway; well, don't go doing it in any spreadsheet that is likely to be read in by another program, or you could cause trouble.