Anchors (^, $) in Bash Scripting - Mini Project: Build & Apply

Using Anchors (^, $) in Bash Scripting

📖 Scenario: You work in a small company where you need to filter log entries. The logs contain many lines, but you want to find only those lines that start or end with specific words.

🎯 Goal: You will write a bash script that uses anchors ^ and $ in regular expressions to find lines starting with a word and lines ending with a word from a list of log entries.

📋 What You'll Learn

Create a variable with multiple log lines

Create a variable with a word to match at the start of lines

Use grep with the anchor ^ to find lines starting with the word

Use grep with the anchor $ to find lines ending with the word

Print the filtered results

💡 Why This Matters

🌍 Real World

Filtering logs or text files to find lines that start or end with specific words is common in system administration and data processing.

💼 Career

Understanding anchors in regular expressions helps automate text filtering tasks, which is valuable for roles in DevOps, system administration, and scripting.

1

Create a variable with log lines

Create a variable called logs that contains these exact lines separated by newlines: error: file not found, warning: low disk space, info: update completed, error: access denied, info: user logged in

Bash Scripting

# Create the variable logs with the exact lines
# Your code here

Need a hint?

Use double quotes and \n to separate lines inside the string.

2

Create a variable with the start word to match

Create a variable called start_word and set it to the exact string error

Bash Scripting

logs="error: file not found\nwarning: low disk space\ninfo: update completed\nerror: access denied\ninfo: user logged in"
# Create the variable start_word with value "error"
# Your code here

Need a hint?

Use double quotes to assign the string.

3

Use grep with ^ anchor to find lines starting with the word

Use echo and grep with the pattern ^$start_word to filter lines from logs that start with the word stored in start_word. Save the result in a variable called start_matches

Bash Scripting

logs="error: file not found\nwarning: low disk space\ninfo: update completed\nerror: access denied\ninfo: user logged in"
start_word="error"
# Use grep with ^ anchor to find lines starting with start_word
# Your code here

Need a hint?

Use double quotes around the pattern and variable to expand it correctly.

4

Use grep with $ anchor to find lines ending with a word and print results

Create a variable called end_word and set it to completed. Then use echo and grep with the pattern $end_word$ to find lines in logs that end with end_word. Save the result in end_matches. Finally, print start_matches and end_matches with echo.

Bash Scripting

logs="error: file not found\nwarning: low disk space\ninfo: update completed\nerror: access denied\ninfo: user logged in"
start_word="error"
start_matches=$(echo "$logs" | grep "^$start_word")
# Create end_word variable with value "completed"
# Use grep with $ anchor to find lines ending with end_word and save to end_matches
# Print start_matches and end_matches
# Your code here

Need a hint?

Remember to use double quotes and variable expansion in the grep pattern. Use echo to print the results.