grep (search text patterns) in Linux CLI - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the grep command do in Linux?

grep searches for text patterns in files or input and shows the matching lines.

beginner

How do you search for the word apple in a file named fruits.txt using grep?

Use grep apple fruits.txt. This shows all lines containing apple in the file.

beginner

What option do you add to grep to ignore case when searching?

Use -i option. For example, grep -i apple fruits.txt finds apple, Apple, or APPLE.

intermediate

How can you count the number of matching lines with grep?

Use the -c option. For example, grep -c apple fruits.txt shows how many lines contain apple.

intermediate

What does the -r option do in grep?

-r makes grep search recursively inside all files in a directory and its subdirectories.

Which command finds lines containing 'dog' in the file 'pets.txt'?

A grep -r dog

B grep pets.txt dog

C grep dog pets.txt

D grep -c dog pets.txt

grep dog pets.txt searches for 'dog' in the file 'pets.txt'.

How do you make grep ignore uppercase or lowercase differences?

A -i

B -c

C -v

D -r

The -i option makes grep ignore case differences.

What does grep -c error logfile.txt do?

A Counts lines with 'error'

B Shows lines with 'error'

C Searches recursively for 'error'

D Ignores lines with 'error'

-c counts how many lines contain the pattern.

Which option lets grep search inside all files in folders and subfolders?

A -i

B -r

C -c

D -v

-r means recursive search through directories.

What does grep -v apple fruits.txt do?

A Shows lines with 'apple'

B Searches recursively for 'apple'

C Counts lines with 'apple'

D Shows lines without 'apple'

-v shows lines that do NOT match the pattern.

Explain how to use grep to find a word in a file and ignore case differences.

Think about the option that ignores uppercase and lowercase.

Describe how to count the number of lines that match a pattern using grep.

Look for the option that counts matches.