CS228 Homework 3

Due Monday, February 5, by 10:30 AM

Homework 3 will be created and turned in just like homework 1, except you should name the file homework3. As before, correct file naming and permissions are part of the grade for the assignment.
Here are the questions for homework 3. Suggested programs to answer the question are given in bold. Most of these require use of pipes. You are welcome to include grep if you like, but it isn't required for these.
Look in /home/data on isoptera. This isn't anyone's home directory, but rather a place where data for bioinformatics research is kept.
Go into the IXI directory in /home/data, and then the questions should make sense.
  1. "dti" stands for "diffusion tensor image", which is a type of magnetic resonance imaging used to visualize connections in the brain. How many dti images are stored in this directory? echo, wc, or ls, grep, wc
  2. Three different facilities have been used to collect images in this directory, HH, Guys, and IOP. These are all hospitals in Britian. How many images are from each hospital? ls, wc
  3. Not all numbers are used. I don't know why. How many images are numbered between 100 and 300? Depending on how you do this, you may end up with a bunch of "No such file or directory" errors. Errors are separate from regular text, and so these won't throw off your answer. ls, wc
  4. Go up one level, and then to the PPMI directory (/home/data/PPMI). Note the capitalization. This is another directory containing MRI images, and in this case, each image is contained inside a directory and is described by an xml file. How many images are in this directory? (hint: Count the xml files) ls, wc
  5. How much data is stored in /home/data? du, man
Here is the command to set the permissions:
chmod 600 homework3
This assignment is worth 35 points, 5 from correct naming, 5 from correct permissions, and 5 from each of the questions above.