Chapter 4 - Working with Text Files

Question 1

Which command to use on a text file to show the first 10 lines?

Answer 1

head

Question 2

Which command to use on a text file to show the last 10 lines?

Answer 2

tail

Question 3

Which option on tail or head command to be used to set the number of lines?

Answer 3

-n option. example : tail -n 5 /etc/passwd shows the last

five lines of the /etc/passwd file

Question 4

What option to use along with tail command on any file that refreshes the display as new lines are added to the file?

Answer 4

-f option. Example : tail -f /var/log/messages

Question 5

Which command is used to filter out a specific field?

Answer 5

cut command. -d option to specify the field delimiter followed by -f with the number of the specific field you want to filter out. Example : cut -d : -f 1 /etc/passwd

Question 6

Which command is used to sort the contents of a file?

Answer 6

sort command. Example : sort /etc/passwd

cut -f 1 -d : /etc/passwd | sort

Question 7

what option to use with sort command to specify which column you want to sort?

Answer 7

-k option. Example : sort -k3 -t : /etc/passwd. -t option is used to specify the delimiter

Question 8

Which command to use to count words, lines and characters?

Answer 8

“wc” command

Question 9

Which command to use to look for that specific string in the file?

Answer 9

grep command. Example : grep anna /etc/passwd

Question 10

Which line anchor is used for looking for Lines Starting with a Specific Pattern?

Answer 10

Example : grep ^anna /etc/passwd

Question 11

What is a Line Anchor?

Answer 11

The type of regular expression that specifies where in a

line of output the result is expected is known as a line anchor.

Question 12

which regular expression to use that states that the line ends with some text?

Answer 12

$
For instance, the command
“grep ash$ /etc/passwd” shows all lines in the /etc/passwd file that end with the text
ash

Question 13

Some of the most Significant Regular Expressions

Answer 13

Regular Expression Use
^text : Matches line that starts with specified text.
text$ : Matches line that ends with specified text.
. : Wildcard. (Matches any single character.)
[abc] : Matches a, b, or c.
* : Matches zero to an infinite number of the previous character.
{2} : Matches exactly two of the previous character.

Question 14

Which are the other two text processing utilities?

Answer 14

sed

awk