Capture groups in Bash in Bash Scripting - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to capture the first word from the string using Bash regex.

Bash Scripting

text="Hello World"
if [[ $text =~ ^([a-zA-Z]+) ]]; then
  echo "First word: ${BASH_REMATCH[[1]]}"
fi

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

A1

B0

C2

D3

Attempts:

3 left

💡 Hint

Common Mistakes

Using BASH_REMATCH[0] instead of BASH_REMATCH[1] to get the captured group.

In Bash, BASH_REMATCH[1] holds the first captured group from the regex match.

2fill in blank

medium

Complete the code to check if the variable 'email' contains a domain using capture groups.

Bash Scripting

email="[e-mail]"
if [[ $email =~ @([a-zA-Z0-9.-]+)\.com$ ]]; then
  domain=${BASH_REMATCH[[1]]}
  echo "Domain: $domain"
fi

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

A1

B0

C2

D3

Attempts:

3 left

💡 Hint

Common Mistakes

Using BASH_REMATCH[0] which returns the whole email instead of the domain.

The domain part is captured in the first group, so BASH_REMATCH[1] holds it.

3fill in blank

hard

Fix the error in the code to correctly capture the year from the date string.

Bash Scripting

date="2024-06-15"
if [[ $date =~ ([0-9]{4})-([0-9]{2})-([0-9]{2}) ]]; then
  year=${BASH_REMATCH[[1]]}
  echo "Year: $year"
fi

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

A0

B2

C1

D3

Attempts:

3 left

💡 Hint

Common Mistakes

Using BASH_REMATCH[0] which returns the full date string.

The year is captured in the first group, so BASH_REMATCH[1] holds it.

4fill in blank

hard

Fill both blanks to capture the username and domain from an email string.

Bash Scripting

email="[e-mail]"
if [[ $email =~ ^([a-zA-Z0-9._%+-]+)@([a-zA-Z0-9.-]+)\.com$ ]]; then
  user=${BASH_REMATCH[[1]]}
  domain=${BASH_REMATCH[[2]]}
  echo "User: $user, Domain: $domain"
fi

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

A1

B2

C0

D3

Attempts:

3 left

💡 Hint

Common Mistakes

Using index 0 which returns the full email instead of parts.

The first capture group is the username (index 1), the second is the domain (index 2).

5fill in blank

hard

Fill all three blanks to capture year, month, and day from a date string.

Bash Scripting

date="2024-06-15"
if [[ $date =~ ^([0-9]{4})-([0-9]{2})-([0-9]{2})$ ]]; then
  year=${BASH_REMATCH[[1]]}
  month=${BASH_REMATCH[[2]]}
  day=${BASH_REMATCH[[3]]}
  echo "Year: $year, Month: $month, Day: $day"
fi

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

A1

B2

C3

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using index 0 for any of the date parts.

The capture groups for year, month, and day are at indices 1, 2, and 3 respectively.