Readings

This week the readings will focus on regular expressions and filters. These additional tools will come in handy when we want to write more advanced shell scripts that slice and dice data.

The readings for Monday, February 22 are:

1. regular expressions:

   • RegexOne Learn Regular Expressions with simple, interactive exercises.

     Work through the Lessons in the Interactive Tutorial.

2. filters:

   • Introduction to text manipulation on UNIX-based systems

Optional Resources:

1. Digital Ocean Tutorials:

   • Using Grep & Regular Expressions to Search for Text Patterns in Linux

   • The Basics of Using the Sed Stream Editor to Manipulate Text in Linux

2. Advanced Bash Scripting - Text Processing Commands

3. The Unix School - Awk & Sed

4. Sed - An Introduction and Tutorial

   Also Grep - An introduction to grep and egrep

5. USEFUL ONE-LINE SCRIPTS FOR SED

6. sed command 20 practical examples

Questions

In your reading06/README.md file, describe what command(s) you would use to accomplish the following:

1. Convert all the input text to upper case:

   $ echo "All your base are belong to us" | ...
   ALL YOUR BASE ARE BELONG TO US
   

2. Parse the /etc/passwd file for the shell of the root user:

   $ cat /etc/passwd | ...
   /bin/bash
   

   Hint: You may need to read up on /etc/passwd

3. Find and replace all instances of monkeys to gorillaz:

   $ echo "monkeys love bananas" | ...
   gorillaz love bananas
   

4. Find and replace all instances of /bin/bash, /bin/csh, and /bin/tcsh to /usr/bin/python in /etc/passwd:

   $ cat /etc/passwd | ... | grep python
   root:x:0:0:root:/root:/usr/bin/python
   mysql:x:27:27:MySQL Server:/var/lib/mysql:/usr/bin/python
   xguest:x:500:501:Guest:/home/xguest:/usr/bin/python
   condor:x:108172:40:Condor Batch System:/afs/nd.edu/user37/condor:/usr/bin/python
   lukew:x:522:40:Luke Westby temp access:/var/tmp/lukew:/usr/bin/python
   

5. Remove any leading whitespace from a string of text:

   $ echo "     monkeys love bananas" | ...
   monkeys love bananas
   

6. Find all the records in /etc/passwd that have a number that begins with a 4 and ends with a 7:

   $ cat /etc/passwd | ...
   rtkit:x:499:497:RealtimeKit:/proc:/sbin/nologin
   qpidd:x:497:495:Owner of Qpidd Daemons:/var/lib/qpidd:/sbin/nologin
   uuidd:x:495:487:UUID generator helper daemon:/var/lib/libuuid:/sbin/nologin
   mailnull:x:47:47::/var/spool/mqueue:/sbin/nologin
   

7. Follow the trailing output of a set of log files.

8. Given two files, show all the lines the are present in both files.

Commands

In the reading06 folder, write at least five summary pages for the following commands:

1. cut

2. sort

3. comm

4. uniq

5. paste

6. tr

7. grep

8. sed

9. head

10. tail

Feedback

If you have any questions, comments, or concerns regarding the course, please provide your feedback at the end of your response.

Submission

To submit your assignment, please commit your work to the reading06 folder in your Assignments Bitbucket repository by the beginning of class on Monday, February 22.