grep with regex (-E) in Linux CLI - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to search for lines containing the word 'error' using extended regex.

Linux CLI

grep [1] 'error' logfile.txt

Drag options to blanks, or click blank then click option'

A-i

B-c

C-v

D-E

Attempts:

3 left

💡 Hint

Common Mistakes

Using -i instead of -E, which only ignores case.

Using -v which inverts the match.

Using -c which counts matches instead of showing them.

The -E option enables extended regular expressions in grep, allowing more complex patterns.

2fill in blank

medium

Complete the code to find lines that start with 'Error' or 'Warning' using extended regex.

Linux CLI

grep [1] '^(Error|Warning)' logfile.txt

Drag options to blanks, or click blank then click option'

A-c

B-v

C-E

D-i

Attempts:

3 left

💡 Hint

Common Mistakes

Using -v which inverts the match.

Using -i which ignores case but doesn't enable extended regex.

Using -c which counts matches instead of showing them.

The -E option allows using the alternation (|) in the regex pattern.

3fill in blank

hard

Fix the error in the code to match lines containing either 'cat' or 'dog' using extended regex.

Linux CLI

grep -E 'cat[1]dog' animals.txt

Drag options to blanks, or click blank then click option'

A|

B*

C.

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using '*' which means zero or more of the previous character.

Using '.' which matches any single character.

Using '+' which means one or more of the previous character.

The '|' symbol is used in extended regex to mean 'or' between patterns.

4fill in blank

hard

Fill both blanks to search for lines containing either 'apple' or 'banana' and ignore case.

Linux CLI

grep [1] [2] '(apple|banana)' fruits.txt

Drag options to blanks, or click blank then click option'

A-E

B-i

C-v

D-c

Attempts:

3 left

💡 Hint

Common Mistakes

Using -v which inverts the match.

Using -c which counts matches instead of showing them.

Use -E for extended regex and -i to ignore case when searching.

5fill in blank

hard

Fill all three blanks to count lines that do NOT contain 'error' or 'fail' using extended regex and ignoring case.

Linux CLI

grep [1] [2] [3] '(error|fail)' logfile.txt

Drag options to blanks, or click blank then click option'

A-E

B-i

C-v

D-c

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up -v and -c options.

Forgetting to use -E for extended regex (though not asked here).

Use -c to count, -i to ignore case, and -v to invert match (exclude lines with the pattern).