BCCS199_Session_13

Question 1

The read command reads input from…?

Answer 1

stdin.

Question 2

The test keyword allows you to make…?

Answer 2

logical tests for branching, looping, etc.

Question 3

Conditional statements in bash are available as …?

Answer 3

if…then…[else…]fi.

Question 4

Loops can be implemented using…?

Answer 4

for…in…do…done.

Question 5

Command arguments in bash scripts are available as…?

Answer 5

$1, $2, $3, etc.

Question 6

The read command reads one line of text from…?

Answer 6

stdin.

Question 7

Format of the read command….?

Answer 7

read var1 [var2 …]

Question 8

The test keyword can be used to test certain conditions in…?

Answer 8

bash:

test condition

Question 9

Appears usually in the context of an…?

Answer 9

if, while, or for statement.

Question 10

test expressions for examining file attributes:

Answer 10

-d FILE : FILE exists, and is a directory.
-e FILE : FILE exists
-f FILE : FILE exists, and is a regular file
-r FILE : FILE exists, and is readable.
-w FILE : FILE exists, and is writable.
- x FILE : FILE exists, and is executable.
FILE1 -nt FILE2 : FILE1 is newer than FILE2

Question 11

test expressions for comparing strings…?

Answer 11

[-n] STRING : the length of STRING is greater than zero.
-z STRING : the length of STRING is zero.
STRING1 = STRING2 : STRING1 and STRING2 are equal
STRING1 != STRING2 : STRING and STRING2 are not equal.

Question 12

logic expressions for the test Command.

Answer 12

EXPRESSION1 -a EXPRESSION 2 : Both EXPRESSION1 and EXPRESSION2 are true.
EXPRESSION1 -o EXPRESSION2 : Either EXPRESSION1 or EXPRESSION2 is true.
! EXPRESSION : EXPRESSION is false.

Question 13

Branching in bash…?

Answer 13

If condition
then
command(s)
else
command(s)
fi

Question 14

The for loop can be expressed like this…?

Answer 14

for VICTIM in list
do
statement(s)
done.

This will loop through every item in list, with $VICTIM representing each one in turn.

Question 15

for loop example:
#!/bin/bash

for F in ‘ls’
do
echo “Oh, look: there’s a file called $F in $PWD!”
done

Answer 15

• Takes the list of files in the current directory, and prints them out with a joyful comment.
• Note the ls, and the reference to the $PWD environment variable.

Question 16

For loops are good for when loops are…?

Answer 16

bounded, i.e. you know how many times to loop.

Question 17

For unbounded loops, use..?

Answer 17

while instead:

while condition
do
statement(s)
done

Question 18

The command line can be accessed with the …?

Answer 18

$0 shell variable.

Question 19

The number of arguments included is represented by the…?

Answer 19

$# shell variable.

Question 20

Each argument is represented by…?

Answer 20

$1, $2, $3, etc.

Question 21

The shift command forces each argument to…?

Answer 21

shift down by one place. This is useful when the number of arguments can vary, or is otherwise unknown.

Question 22

The rpm command is used to..?

Answer 22

add or remove software from your system

Question 23

You must have root privileges to…?

Answer 23

add and remove software with rpm.

Question 24

Anyone can query installed packages, or…?

Answer 24

package files.

Question 25

Installed packages are maintained in the…?

Answer 25

rpm database.

Question 26

Queries can be made of the database with the…?

Answer 26

-q switch.