Grep Command

Question 1

What is the grep command?

Answer 1

global regular expression print – picks the strings or pattern from the text of a file or output of a command

Question 2

What is the basic difference between the "grep" and "find" commands?

Answer 2

grep finds the pattern or strings in data, find is used to find files and directories.

Question 3

How can I find the pattern/string "root" from the /etc/passwd file?

Answer 3

grep root /etc/passwd

Question 4

How can you find the patterns/strings "root|failed" in the "/var/log/secure" file?

Answer 4

egrep
“root|failed” /var/log/secure

Question 5

How can we extract all the lines that contain the word "error|ERROR" in "/var/log/messages"?

Answer 5

grep -i error /var/log/messages or egrep “error|ERROR” /var/log/messages

Question 6

How can we obtain logs that pertain to "sshd" from the Security logs?

Answer 6

grep sshd /var/log/secure

Question 7

Use grep and search for the string "usb" from the file that contains hardware messages?

Answer 7

grep usb
/var/log/dmesg

Question 8

How can we find all the lines in "/etc/passwd" that do not contain the string "root"?

Answer 8

grep -v root
/etc/passwd

Question 9

How can I determine the number of occurrences of the string "Robert" in a text file using the command line? Please provide the necessary command to achieve this.

Answer 9

grep -o Robert file.txt | wc - l

Question 10

Which flag would you use to ignore case sensitivity while you grep a pattern?

Answer 10

-i to ignore case
sensitivity