“ROOT Filesystem is Currently Mounted Read Only”

This error can be a bit unnerving if your Linux system doesn’t reboot cleanly. To remount your root filesystem as read/write (rw) issue this command:

 

# mount -n -o remount rw /

Backup GMAIL with FetchMail

If you’re anything like me you really enjoy GMail but you really enjoy the peace of mind and comfort in having a local imagecopy of your email available at all times. I tend to not rely heavily on services provided by third party providers, even Google. What if I am offline? What if they have a long outage and I need access to my mail? As a society, we rely heavily on mail… probably more than we really know. Think about it: When was the last time your companies mail server went down? Global anarchy, chaos and fires result.

 

In this tutorial I will install, configure and run fetchmail to retrieve my messages over POP on a CentOS server.

 

Backing up GMail

Here we go 🙂

 

1. Check to make sure fetchmail is installed on your system.

     # rpm -aq | grep fetchmail

If fetchmail is installed you will see the package returned. If not, issue this command in CentOS:
    # yum -y install fetchmail

2. Good, now we have fetchmail installed. Let’s verify by using this command:

     # fetchmail -V | grep release
        This is fetchmail release 6.2.5+IMAP-GSS+RPA+NTLM+SDPS+SSL+INET6+NLS

3. Let’s create a user which will keep our gmail backup.

     # adduser gmailbackup

4. Let’s create a fetchmail configuration file called ".fetchmailrc" in your current users home directory.

     # vi ~/.fetchmailrc

5. In this file enter the following substituting your credentials where necessary:

     poll pop.gmail.com with proto POP3 and options no dns
     user ‘[email protected]’ there with password ‘yourpassword’ is ‘gmailbackup’ here  options ssl

6. Now let’s set the permissions on the new .fetcmailrc file otherwise fetchmail will complain like this:
        File /root/.fetchmailrc must have no more than -rwx–x— (0710) permissions.

To set these permissions use this command:

      # chmod 710 ~/.fetchmailrc

7. Let’s fetch the mail with verbosity on.

      # fetchmail -vk

8. Let’s verify the mail we downloaded
      # mail -u gmailbackup

9. After this transfer let’s set up a cron entry to run a fetch every hour for safe keeping of our GMail.

      # crontab -e

    Add this to the bottom of your users cron:
          0 * * * * root fetchmail -k &> /dev/null

    The above redirects all output from fetchmail to /dev/null so we don’t get chatter in our local users mail box.

 

That’s it! You’re all done and being backed up. For easier viewing, assign a password to your local gmailbackup user with "passwd gmailbackup" and use a web client like RoundCube or SquirrelMail to view your GMail backup.

Using SFDISK to backup your partition table

Many times we perform full backups of the root partition (/), including all mount points under root. How often do we back up our partition tables? What if we have total disk failure and our only restore option is a file-level restore? Will we know what our partition sizes were? Enter sfdisk.

 

Using SFDISK

The most common usage of sfdisk is to dump the partition sizes and count to a file for later import. This partition table dump can be included in your gzipped tarball.

Use this command to dump /dev/sda’s partition table:

# sfdisk -d /dev/sda > /backup/sda.part

 

The dump file will look like this:
# partition table of /dev/sda
unit: sectors

/dev/sda1 : start=       63, size=479990007, Id=83, bootable
/dev/sda2 : start=479990070, size=  8385930, Id=82
/dev/sda3 : start=        0, size=        0, Id= 0
/dev/sda4 : start=        0, size=        0, Id= 0

Restoring Partitions from SFDISK Dump

To restore your partition table from a dump file use this command:

# sfdisk /dev/sda < sda.part

Linux: The Sticky, SUID and SGID Bits

I’m sure anyone who has used Linux has heard of the Sticky, SUID or SGID bits. The most common (and easiest to explain) is the infamous "Sticky Bit".

 

 

The Sticky Bit

Back when systems had kilobytes of RAM (instead of gigabytes), this bit was used to mark a file (program) to run, and remain, primarily in memory. This was a great benefit back in "the day". Now the most common use for the sticky bit is to maintain the integrity of publicly accessible directories.

Setting the Sticky Bit

To set the sticky bit use this command:
# chmod +t <file/directory>

 

Looking for the Sticky Bit

To identify the sticky bit use the standard "ls" command to show all files. Look for a (t) in the listing.

For example:
-rw-r–r-T  1 root root 0 Jul 14 21:14 foo

 

The SUID Bit

SUID stands for "Set User ID". The SUID makes the program run as the user who owns the program (instead of the current user). I have an application called "test" which is owned by "dale" and the user "al" runs "test" the program will still run as "dale" if the SUID bit is set.

 

Setting the SUID Bit

To set the SUID bit use this command:
# chmod +s <file/directory>

 

Looking for the SUID Bit

To identify the SUID bit use the standard "ls" command to show all files. Look for an (S) in the listing.

For example:
-rwSr-Sr–  1 root root 0 Jul 14 21:14 foo

 

The SGID Bit

The SGID bit is much like the SUID bit but runs a program only as the set group ID group.

 

 

Examples

Setting SUID for user and not group
# chmod u+s <file/directory>

Setting sticky bit for group only
# chmod g+t <file/directory>

Green: China’s New Landmark Structure

Photo Courtsey WikipediaIt looks like China has erected a new landmark structure that is composed of over 2,200 LED lights over 24,000 square feet. It uses photovoltaic technology to convert sunlight directly into electricity.  The picture on the right is a photovoltaic tree in Sydney, Australia.

imageThe structure was created by a New York based architect who says it functions like an organic system. The system takes all the power it can get during the day and stores it for displays at night. 

 

 

[ Read more at CNN.com ]

Top 10 Worst Case Mods of All Time

Well I was browsing around a bit on the Internet today and I noticed that there are some really, really horrid case modifications that made their way to the ‘net. I tend to lead toward case modifications that add some functional value and maybe the occasional aesthetic tweak. These cases are just absurd.

Here is a list of the Top 10 Worst Case Mods of All Time.

 

10. The "Pulling open a hole in the side of my computer" mod
image

Ok. What is this all about? I get it, you’re pulling open a hole in the side of your case with what looks like hands. There must be something really powerful inside to deserve a red light. Seriously?

 

9. The "Tortise Beetle"
image

I think I’m stuck in the middle of a rave. What is this? Is this a computer or the geekiest glow stick ever created. Two thumbs down. Wayyyy down. [mini-itx.com]

 

8. The "Magna Doll" Mini-ITX Computer

image image

Just when I thought it couldn’t get any worse, I found a case that some poor old chap converted into a doll. Perhaps he thinks his computer is a real woman? This just creeps me out.

 

7. The "Put all my computer parts in a cardboard box" mod

image

This is by far a horrible case mod. This is no new trick but yet people still seem to stuff their parts in a piece of cardboard and think it’s cool. I think this is a bad idea. What if you need to take your computer out of the house when its raining? Sure, use an umbrella, but if any water gets on the "case" your hard drive might fall out. Oh and also, I’ve seen power supplies catch on fire…. if it were a real case it wouldn’t be used as kindling to start a house-destructing fire.

 

6. The "I just crapped out something, plugged it in and it’s now my computer" mod

image

No further comment needed.

 

5. The "Let my gerbil run through my PC" mod

image

Well.. this case mod is pretty cool if you’re a gerbil lover. I’m not sure that the heat or the noise would really be a good thing for your animal. This person spent over forty hours on this case. I really don’t see this as time well spent 🙁

 

4. The "I have too much free time" mod
image

This case mod is almost as creepy as the girl above. The difference betweent his one and the one above is that this one looks like it took longer to make. I’m not sure why people spend their time making things like this but maybe it’s their real passion. Weird.

 

3. The "I ran out of ideas so I just sprayed foam-sealant all over my computer parts" mod

image

This modification baffles me. Why would someone spray foam all over their parts? I’m not quite sure how the video card or other add-on cards breathe for that matter. I bet this was a good idea at first. When the video card dies… might as well spray a whole new "case" on. [More here]

 

2. The "almost cooler than a regular cardboard box" mod

image

Why must people insist on stuffing their parts into a cardboard box? /facepalm

 

1. The "Hang all my parts from cat5/6 strands because I don’t want a case" mod

image

Wow. Well… This is the crappiest case mod of all time because it really isn’t a case mod at all. This is … lazy and a bit amusing at the same time.

Conclusion

Please be sensible when modding your cases. Sure its all about fun but really functionality should be considered. Also, making your computer into a woman is a little scary 🙂

10 Top Downloaded Firefox 3 Themes

Most of us already have Firefox 3 downloaded and installed. If you don’t, head over to Mozilla.com and download a copy.

So here it is, a quick list of the top downloaded themes for Firefox 3.

 

1. Aero Fox

image

I like this template because the black is a bit easier on the eyes. The icons are a little nicer and seems to have a more futuristic look to it. Get it here.

 

2. NASA Night Launch
image
This theme is pretty interesting. I guess it just depends on how much of a NASA enthusiast you are. I really like the dark looking theme that most people are going with. This theme should be supported more on the soon to come Ubuntu 8.10 as they’re working more on dark theme support. Get it here.

 

3. Aero Silver Fox

image

Not quite as nice as the original black Aero Fox but I really like the rounded feel. The black is still the best in my opinion. Get it here.

 

4. Aquatint Black Gloss
image

Can you see an obvious trend lately? It looks like the masses really enjoy the black background and rounded icons. I really like this theme as its simple yet effective. Get it here.

 

5. Pitch Dark for Fx
image

This one is a little odd for me but it has a good place in our top downloaded selection. This theme was designed to keep maximum visibility, usability and to provide maximum screen real estate. This one really works well on my widescreens. Get it here.

 

6. Vista on XP
image

This theme is a top download probably because people want the Windows Vista “feel” on their XP systems. Why I do not know :-). I think it’s because they want to experience the glamour without the suck. Get it here.

 

7. Qute
image

It seems like the masses really believe in simple and effective themes. I couldn’t agree more since the internet seems to be laden with useless junk. Why not have a browser that is simple and just does what it’s supposed to do? Get qute here.

 

8. myFireFox

image

Just when you thought the Vista on XP theme was a little odd. This theme lets your Firefox look just like IE7. WHAT? Why would you want to take away the look of Firefox and convert it to one of its less-worthy counterparts? I don’t get it /facepalm. If you want to steal the soul from Firefox get the theme here.

 

9. Abstract Zune
image

Yet another odd name/theme. It looks like the Microsoft theme is still prevalent here. I do, however, like the black look that this theme has. Not too keen on the orange, however. Get it here.

 

10. iFox Smooth
image

I’m not too sure about this theme either. I like the idea and I like the clean interface. Firefox just isn’t an iPod no matter how hard you try. Get it here.