The University of Massachusetts Amherst

Month: May 2015

Categories
Linux

Understanding the Rsync Utility

We’ve all had a file scare sometime in our computing careers. In many cases, the computer won’t show any signs of corruption until everything starts to fail at once. When things do go wrong, your first thought is always about the safety of your files – will you be able to recover them?

If you had backed up your files regularly with a backup utility, you wouldn’t have to worry about whether you would be able to recover all of your data. However, many people do not see the value in doing regular backups, because they think that it is a waste of time. Their rationale is that the probability that a computer will need to access the backup is small enough that waiting for the computer to copy over all of their files every time they do a backup is pointless.

Rsync is an intelligent backup utility. Instead of duplicating the entirety of the data which is being copied over (looking at you cp), rsync will calculate the differences between what is being copied and what already resides in the directory, and will only copy over the differences. If the creation time and size of a file have not changed, rsync will move on without making any copies. This saves lots of time, which would have been spent on doing costly I/O operations. Rsync will take about as long as cp to complete the first time a backup is made, but subsequent backups could be done in a matter of minutes instead of hours, depending on the frequency with which you back up your system.

Rsync also includes a lot of flags which can help with the backup process.

–exclude is useful for ignoring large directories. If a full linux backup is being made, directories like /var and /proc will be excluded due to their huge size and session-specific information.

–delete will remove anything which is present in the backup directory which is not present in the source directory. This is mostly useful for creating snapshot copies of a system. If you would rather keep every file backed up, even if you delete it on your own system, this flag is not necessary.

–archive, also known as -a, is another useful flag. It is equivalent to the flags -rlptgoD. It performs a snapshot archival of the specified system. I’ll go into the individual flags in more detail below.

  • The -r flag stands for recursion. It tells the program that you want it to copy the contents of a directory as well as its shell. If this flag is not set, you will have an unhappy TA on your hands, looking at a series of empty directories.
  • The -lptgo flags preserve the information on a certain file. If these are not set, new creation information is created for each newly generated file, indicating the permissions, owner, etc. of the directory where the copied information is going to be stored. To keep the creation information on the original file intact, -l preserves links between files, -p preserves the permission of the file, -t preserves the creation time of the file, -g preserves the group the file is associated with, and -o preserves the owner of the file.
  • The -D flag is the most optional of all of the backup information. It preserves information on the devices and any special files which are mounted at the time of the backup.

Finally, rsync has flags which let the user know what is going on during the backup process. The -v flag stands for verbose. It outputs the current step on the screen, so the usre will know how far into the backup they currently are. Since this is an I/O operation, it will slow down the overall program, but many people believe that this kind of knowledge is worth the tradeoff. In order to further modify the -v flag, you are also able to set the -h (human-readable) flag, which makes any sizes that the computer outputs be rendered as MB and GB, as opposed to full byte numbers.

This is an example of an rsync script command, which will take a snapshot of whatever is in folder 1 and store it in folder 2, deleting anything in folder 2 which is not in folder 1 and telling you everything that it is working on in between:

rsync -av –delete /home/folder1/ /home/folder2/

 

Categories
Android Apps Operating System Windows

New Dual-Boot Android/Windows Phone

Ever wanted to have an Android phone but still be able to play Xbox Live games on mobile? Soon you’ll be able to!

An upcoming handheld developed by a Chinese company called Elephone will be able to do just that! The new phone rumored to be arriving in June will reportedly be able to dual-boot Android 5.0 and Windows 10 giving you the best of both worlds.

 

 

Although Windows phones are not nearly as common as Android devices and iPhones, they are still packed with plenty of useful features.

  • Full Microsoft Office Suite. Word, Excel and Powerpoint are included on all Windows 10 phones. The Suite will work the same on your phone as it does on your desktop with minimal compromises. Outlook and Calendar are also being revamped for 10.
  • Xbox Live gaming on your phone. Currently with the Xbox Live app you can tweak your avatar, check achievements and Gamerscore and message your friends. Using the SmartGlass app from the Windows Phone store you can navigate your Xbox dashboard, start and pause movies, and view information about your games and videos. In Windows 10 Microsoft is planning to be able to allow users to play Xbox Live games on their phones. Although the list is short Microsoft is working to integrate mobile and Xbox multiplayer capabilities.

  • More Space! When you sign up for a Microsoft Account you get 7 GB of free space on their OneDrive cloud-based storage. You can automatically sync your photos and videos to your account.  You’ll be able to able to access all your content through your Xbox on the big screen.
  • Messaging. With inline messaging you’ll be able to send text messages and Skype messages through one app. You can also resize and drag the keyboard around for more one-handed usability.
  • Cortana. Windows’ version of Siri can assist at making phone calls, texting, making calendar events and setting reminders, control alarms and music, set up directions and help you find places to go. You can ask Cortana about certain facts, ask her to check sports scores, suggest weight loss workouts, and find out how the Dow Jones did today.

With the dual-OS option you’ll be able to access all those great features and at the same time run Android Lollipop which has a whole slew of unique features itself:

  • Access to the Google Play Store which contains the most mobile apps ( over 1.3 million) compared to the iOS app store, Amazon Appstore and Windows Phone store. You can also download movies, books, and music.
  • Full integration of Google Services. Out of the box Android phones come equipped with apps like Gmail, Maps, Play Music, Hangouts, YouTube and Google Drive. It’s handy having everything in one Google folder on the home screen.
  • Google Now. Although originally a Google Search application, Now can do everything Cortana and Siri can do. Google has announced that they will also begin supporting third party applications such as Pandora, Duolingo and Lyft, among others.
  • Open Source. It’s easier to design and program applications for Androids as they are written using the Java coding language. There is a lot of documentation out there and free programs where one can learn to develop mobile applications.

Elephone is planning on releasing two phones, one just with Android and the second with the dual boot capabilities. Both versions will have large 5.5-inch 2K displays (1440 x 2560), 4 GB of RAM and 32 GB of built in storage. There will also be a a battery reported to exceed 3800 mAh  For reference, the Samsung Galaxy S5 has a 2800 mAh battery and advertised for 21 hours of talk time.

There are slight differences in the 2 handhelds as the Android version of the phone will contain a 64-bit octa-core processor while the dual-OS phone will only contain a quad-core chip. Also, the Android-only handset will come with a 21MP camera while the dual version will only be 20.7MP. Both are expected to also come with fingerprint scanners.

If you, like myself, have been used to the Android interface but want to see what’s different or special about the mobile Windows OS you’ll be able to get both without sacrificing anything. Elephone is already popular outside of the United States for making affordable Androids so it’ll be interesting to see if they make any impact in the US market.

Categories
Hardware

No one wants to touch your dirty keyboard.

Between my job as a consultant here and on my travels using other peoples computers, I have developed only one irrevocable, unavoidable, instinctual pet peeve. No, it’s not 42 tool bars in a browser, non-activated copies of Windows, or even vicious malware. I can deal with those. What bothers me the most is a dirty computer. A grimy, sticky, slightly yellowed keyboard with a splattered screen.

Please understand that just like door knobs, steering wheels and phones, your keyboards will be handled more then anything else in your entire day. If more then one person uses that same computer, then there is two people who have effectively swapped any grime, dirt, sickness or whatever else you call it. Normally, I’d be fine with this cesspool of microorganisms, but I’ve seen from experience how much more myself and others get sick when in huge, dense populations for a long time. So, it’s better safe then sorry to clean your computer, and rest assured that there’s one less thing that won’t get you sick.

1.) Cleaning your Keyboard and Mouse

Cleaning a keyboard is easy. I try to do my personal ones about once every few weeks, but for shared keyboard I’d say go for once a week or even once a day. The best method I’ve found is using certified keyboard wipes, which will not harm any electronic compliments in the keyboard. Trust me, do not just use any wet disinfecting wipe, I’ve lost a favorite wireless keyboard this way, and I’d hate to imagine what it would do to a laptop.You can just take a cloth, and wipe gently across the keyboard with it. If there are any problem spots, just add a little elbow grease.

You can do the same thing with a computer mouse and tracpad, just be sure to use only the recommended wipes.

I like these wipes, but any are good, as long as they are KEYBOARD WIPES!

 

2.) Clean your Screen

Screens are tricky. Matte screens, as much I would like to clean them, are almost impossible to get clean, as there will always be streaks left over. You can try using “dry wipes”, but results may vary. My advice: don’t get your screens dirty.

Touch screens and the screens on most Macbooks- ie “Glass” Screen- are different. For there, you can use approved isopropyl alcohol wipes, which come in convenient little packages that you buy in a box of 20 something. You simply open the package, unfold the wipe, and wipe. You should be done when the wipe is dry. You can also use any other approved isopropyl screen cleaner. To get rid of streaks, use a microfiber cloth afterwords.

Protip: While powered off, put your laptop on it’s top while cleaning, so the screen on the desk, and the body of laptop is against your body. This  will eliminate stress on the hinges of the screen.

Again, do not use any non certified wipes, as they may cause damage.

Box of screen wipes

 

Categories
Web

Career Planning Online

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Now that you have graduated you may be thinking about the future. On the other hand, you may not be thinking about the future. Either way, enjoy your week of cap throwing, social gatherings, and parents. Maybe you got a cool graduation gift from that uncle or you’re just taking some time off or you are traveling the world. No matter what, reality may hit you sooner rather than later if you don’t have a job lined up.

If you are really late in the game, the government offers an interesting career path tool. That can help you figure out what you want to do with your life. Check out My Next Move to see where you should be going with your life.

Another under-appreciated resource is Linkedin. Recruiters are constantly combing through profiles and reaching out to potential employees whose skills match the job descriptions of the positions they are trying to fill. There has been an increasing expectation for job seekers to have a Linkedin account, so having an up-to-date profile could be the difference between an interview and a paper shredder.

You can also check out services for UMass Alumni from UMass Career Services. Career Connect, a tool to search for jobs and internships and update your resume, is available for one year after graduation. Just keep in mind that Career Services will be transitioning to a new service this summer, so be sure to backup your resume and job postings by May 20th. As an alternative, a similar non-UMass affiliated job search tool is Indeed.

Whether you are a senior leaving high school or a recent graduate from UMass, knowing where to go next may be daunting.

Maybe you already have a job lined up and you know exactly what you want to do with your life and what you will do with your first pay stub. No matter what, you can still check out this online career tool. When I found this website today I didn’t intend to use it to discover my calling. Instead, I tried switching the answers in my head to see what my opposite result would be. This was a fun game. My career “opposite” was midwife. Not that there is anything wrong with being a midwife, it just isn’t for me.

Congratulations and good luck!

Categories
Operating System

The Intel Computing Stick is the future that we are probably not ready for (yet)

Intel Compute StickThe world’s first electronic computer, the ENIAC, is probably bigger than the room you are sitting in now, and caused mini-blackouts whenever it was in use. That was back in 1946, and 69 years later, Intel has released the Intel Compute Stick, a computer that’s light years faster than the aforementioned monstrosity, small enough to disguise itself among a pile of USB flash drives, and runs on so little power that it adds maybe 2 cents to your next electric bill.

At the price of $150, the Compute Stick runs Windows 8.1 or Ubuntu, has a respectable 32GB hard drive, 2GB RAM, wi-fi, USB, the goods. It is meant to be a fully functioning computer, and setting it up includes plugging the stick to a USB port for power, and the stick itself to a HDMI port on a TV or monitor.

You cannot help but feel a little astonished at how much Intel was able to pack into such a small package. Yet the first rendition of the Intel Compute Stick has so far been met with a fairly uniform reaction: fantastic idea, iffy execution. Turns out the Compute Stick was too small for its own good: it needed an HDMI monitor to be of any use; there is only one USB port to be used between a mouse, keyboard, and other peripherals; and since the Compute Stick is so low powered, it cannot reliably power both Bluetooth and Wi-Fi at once.

So despite its tablet-grade specs and ability to run Windows 8.1, the Compute Stick falls short of being a justifiable PC replacement. A lot of the Compute Stick does not scream “practical”; instead it looks to please the very small niche of users who simply want a plug and play device that can handle browsing the web and streaming Netflix. It will probably explode if you run GTA V, though.

Ironically, while there is value in the Compute Stick’s ultra-mobility, it is also what hinders the Compute Stick from becoming a viable replacement for your computer. Intel needed to strike a balance between affordability and performance with the Compute Stick, and the result was an underwhelming performance complemented at a decent price. With the Compute Stick, however, Intel might be onto something. Whatever they do with the next iterations of the Compute Stick will determine its fate as a niche product or a mainstay in the future.