Difference between revisions of "CSC220 Lab 1 2010"
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Revision as of 15:12, 7 September 2010
You can work in pairs on this lab if you wish. Otherwise work individually.
Contents
Login
- Login to a Linux box around you using your CSC220a account.
Path-Related Questions
- Question 1
- What is the path of your account? In other words, what subdirectories does one have to traverse to reach your account.
- Question 2
- What other subdirectories are at the same height as yours in the directory tree?
- You will notice that all user accounts are in a major directory called Users. The old standard for users on a linux system is to have the users in a directory called home in the root directory.
- Question 3
- You will notice that some user accounts still exist in home. Which are they?
Questions about File-Searching
- With Linux, the name of the printers supported are listed in a file called /etc/printcap. Look at its contents.
- Question 1
- Figure out a way to get only the entries from this file that represent printers that are in Ford Hall.
Filtering Log Files
- Open a browser window and load up the following URL: http://maven.smith.edu/~hadoop/log.txt
- Notice that it is a long log of the output of a research program I have been running recently. It is very long and contains a lot of information: some useful, some not.
- You are going to get a copy of this file into your account. Instead of copying and pasting the text into a file, you are going to use a useful utility called wget. Wget is a Linux utility that allows you to grab Web pages from Web sites, without using a browser.
- Try it:
wget http://maven.smith.edu/~hadoop/log.txt
- Check that the file is in your directory
- Question 1
- How many lines of text does the file contain?
- Question 2
- The second question is to list only the lines that list the real execution time. These lines look like this:
real 23m6.777s
- Go ahead, list the real execution times. What is the shortest time recorded? The longest?
- Question 3
- List not only the real execution times, but also the lines of the form:
processing noTasks = 17240 maxNoTasks = 8, splitSize = 33554432L
- The output should look something like this:
processing noTasks = 862 maxNoTasks = 8 splitSize = 33554432L real 22m11.284s processing noTasks = 862 maxNoTasks = 16 splitSize = 33554432L real 0m13.113s processing noTasks = 1724 maxNoTasks = 8 splitSize = 33554432L real 0m10.891s processing noTasks = 1724 maxNoTasks = 16 splitSize = 33554432L real 0m40.891s processing noTasks = 80 maxNoTasks = 8 splitSize = 33554432L real 2m54.601s
Pipes
- Question 1
- How many users have accounts on grendel (or beowulf)?
- Question 2
- Who are the three users who have modified their account most recently?
- Question 3
- Same question, but the three who haven't modified (or touched) their account for the longest time?
- Question 4
- Who are the users who have modified their account today?
More challenging pipes
- Use emacs to create the following program in your 220a account: stdouterr.py
- Make your program executable
chmod +x stdouterr.py
- run your program
./stdouterr.py
- observe the long output. If you observe closely the listing, you will discover that some lines contain error codes, of the form
Error 404: blue screen alert!
- Question 1
- run the program and filter its output so that you see only the lines containing error messages
- Question 2 (tricky)
- How many lines are output by the program?
- Question 3 (trickier)
- run the program and use commands that will display only the number of Error messages