Regular Expressions

This first section contains questions regarding regular expressions and common UNIX tools used in this course.

 

Question 1

"[0-9][0-9][0-9]" is an equivalent expression to "[0-9]{3}"

  

True

 

  

False

 

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Question 2

The expression "[[:alpha:]]+" is equivalent to "[A-Za-z]+"

  

True

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False

 

 

Question 3

Which of the following commands will change all occurrences of dog in the file animals.txt to mutt before printing them to the terminal?

  

sed -s "dog" "mutt" animals.txt

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sed 's/dog/mutt/g' animals.txt

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grep -s "dog||mutt" animals.txt

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at animals.txt | grep -c "dog" "mutt"

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Question 4

Which answer is true about the following regular expression;

"(xyz)"

  

Matches "xyz" anywhere in a line

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Matches "xyz" ONLY if it touches a word boundary

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Matches either the letter x, y or z once

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Matches any combination of x, y and z

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BASH Scripting

The following questions are specific to BASH scripts and their syntax.

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Question 5

The first line of this script is a convention unique to BASH scripts. It tells BASH that the file is a script.

@!/bin/bash echo -e "Hello, World!"

  

True

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False

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Question 6

Which of the following is not true regarding if statements in BASH scripts?

  

They can optionally contain as many elif statements as needed

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They must contain the 'else' keyword

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They must contain the 'then' keyword

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They begin with an 'if' keyword and end with a 'fi' keyword

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Question 7

Line 5 of this script is a 'comment' and will not be executed

     1  #!/bin/bash     

     2  declare -l MYVAR='ORB'     

     3  if [ $MYVAR == "ORB" ]; then     

    4          VAR1=3     

    5          #echo $MYVAR     

    6  fi

  

True

​

  

False

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Awk

The following questions pertain to the Awk scripting language and awk command syntax.

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Question 8

Which of these is NOT true regarding awk?

  

Awk can accept input from stdin, a named file or the terminal directly

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The number of fields must remain constant between records

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Data files are divided into records using the contents of the RS variable

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Records are spereated into fields using the contents of the FS variable

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Question 9

The command awk '{print $1}' demo.txt prints the first line of the file demo.txt

  

True

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False

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Question 10

Which of the following is not a built-in awk variable?

  

OFS

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ORS

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OFMT

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NR

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ORB

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Question 11

When passing variables to an awk script file; the -v option must be specified if you would like to access the variable in the post-processing section of your script.

  

True

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False

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Perl

The following questions are specific to the Perl scripting language and its syntax.

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Question 12

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The statements in a while() code block will always be executed at least once.

  

True

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False

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Question 13

An array can be converted to a string using this function;

  

join

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paste

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glue

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merge

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Question 14

The following script is incomplete. Select the answer that will correctly replace the ??? and produce the desired output.

myScript.pl

# Interpreter line intentionally omitted! %cardinal = (     "N" => "North",     "E" => "East",     "S" => "South",     "W" => "West", ); ???

Invocation and output

$ ./myScript.pl East

  

print $cardinal{"East"};

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print %cardinal["E"];

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print $cardinal{"E"};

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print @cardinal["E"];

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Question 15

The pragma use strict; requires that variables be declared before they are used.

  

True

 

  

False

 

 

Question 28

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Perl is a case sensitive language.

  

True

​

  

False

 

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Question 16

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If there is a newline character at the end of a string, this function removes it.

  

trim

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chomp

 

  

clamp

 

  

chop

 

 

Question 17

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The following script is missing its interpreter line (represented as ???). Select the correct answer to replace the ???.

??? use strict; my $VAR=100; print $VAR . "\n";

  

#!/bin/bash

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#!/usr/bin/perl -e

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#!/usr/bin/perl

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use /usr/bin/perl

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#!/bin/sh

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Python

The remaining questions are related to Python and its syntax. This is the last section of this exam; keep going!

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Question 18

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Which of the following is correct regarding dictionaries in Python?

  

All of these are true

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Keys must be unique

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hey work like associative arrays of hashes found in Perl and consist of key-value pairs

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A dictionary key can be almost any Python type, but are usually numbers or strings. Values on the other hand, can be any arbitrary Python object, but strings are most commonly used

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Question 19

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The output of the following Python statement will be "llo Wo"

myString = "Hello World" print(myString[2:7])

  

True

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False

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Question 20

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In python, we can import additional functionality using;

  

packages

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libraries

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components

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modules

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Question 21

The operation performed on myList within line 2 is referred to as a _____________ .

myList = [0,1,2,3,4,5] subList = myList[:3]

  

subsequence

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slice

 

  

splice

 

  

subdivide

 

 

Question 22

Like Awk and Perl; double quotes in Python can be used for string expansion, while single quotes are used for literal strings.

  

True

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False

 

 

Question 23

Given the partial script below; select the correct statement that would read a single line from standard input.

#!/usr/bin/python import math import random import sys ...

  

sys.readline()

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stdin.readline()

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sys.in.readline()

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sys.stdin.readline()

 

 

Question 24

The following Python script will not execute because there is an important statement missing. Enter the needed statement in the provided blank.

#!/usr/bin/python ???????? myVar = random.randint(0,100) print("The number of the day is %d!" % (myVar) )

  

No Answer

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Something Else

 

  

import random

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Question 25

In Python, the readline() function automatically removes the newline character at the end of a line.

  

True

 

  

False

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