Regex match (~, ~*) in Nginx - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to match URLs ending with .jpg using a case-sensitive regex.

Nginx

location ~ [1] { }

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

A\.jpg$

B^jpg$

Cjpg$

D\.JPG$

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting to escape the dot in the regex.

Using case-insensitive operator (~*) instead of case-sensitive (~).

The ~ operator in nginx is for case-sensitive regex matching. The pattern \.jpg$ matches strings ending with '.jpg'.

2fill in blank

medium

Complete the code to match URLs ending with .PNG or .png using a case-insensitive regex.

Nginx

location ~* [1] { }

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

A\.PNG$

Bpng$

C\.png$

D^png$

Attempts:

3 left

💡 Hint

Common Mistakes

Not escaping the dot.

Using ~ instead of ~* for case-insensitive matching.

The ~* operator in nginx is for case-insensitive regex matching. The pattern \.png$ matches strings ending with '.png' or '.PNG' or any case variation.

3fill in blank

hard

Fix the error in the code to correctly match URLs starting with /images/ using a case-sensitive regex.

Nginx

location ~ [1] { }

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

Aimages/

B^/images/

C^images$

D/images/

Attempts:

3 left

💡 Hint

Common Mistakes

Omitting the caret ^ causes matching anywhere in the string.

Missing the leading slash in the pattern.

The caret ^ anchors the regex to the start of the string. To match URLs starting with '/images/', use ^/images/.

4fill in blank

hard

Fill both blanks to match URLs ending with .css or .js using a case-insensitive regex.

Nginx

location ~* [1] { } # matches files ending with [2]

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

A\.(css|js)$

B\.(jpg|png)$

C.css$

D.js$

Attempts:

3 left

💡 Hint

Common Mistakes

Using separate patterns for .css and .js instead of combined.

Not escaping the dot.

The regex \.(css|js)$ matches strings ending with '.css' or '.js'. Using ~* makes it case-insensitive.

5fill in blank

hard

Fill all three blanks to match URLs starting with /api/ followed by digits, case-sensitive.

Nginx

location ~ [1][2][3] { }

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

A^/api/

B\d+

C$

D[a-z]+

Attempts:

3 left

💡 Hint

Common Mistakes

Omitting anchors causes partial matches.

Using wrong character classes for digits.

The regex ^/api/\d+$ matches URLs starting with '/api/' followed by one or more digits until the end of the string.

Practice

1. What does the ~ operator mean in an nginx location block?

easy

A. It matches any request regardless of URL.

B. It performs a case-insensitive regular expression match.

C. It performs a case-sensitive regular expression match.

D. It matches the exact string only.

Solution

1. Step 1: Understand nginx regex operators

   The ~ operator in nginx is used for regex matching that is case-sensitive.

2. Step 2: Differentiate from ~*

   The ~* operator is for case-insensitive regex matching, so it is different from ~.

3. Final Answer:

   It performs a case-sensitive regular expression match. -> Option C

4. Quick Check:

   ~ = case-sensitive regex match [OK]

Hint: Remember: ~ is case-sensitive, ~* is case-insensitive [OK]

Common Mistakes:

• Confusing ~ with ~* for case sensitivity
• Thinking ~ matches exact strings only
• Assuming ~ matches all requests

2. Which of the following is the correct syntax to match URLs case-insensitively using regex in nginx?

easy

A. location ~* /images/ { }

B. location = /images/ { }

C. location ~ /images/ { }

D. location /images/ { }

Solution

1. Step 1: Identify case-insensitive regex syntax

   In nginx, ~* is used for case-insensitive regex matching.

2. Step 2: Check other options

   ~ is case-sensitive, = is exact match, and no operator means prefix match.

3. Final Answer:

   location ~* /images/ { } -> Option A

4. Quick Check:

   Case-insensitive regex = ~* [OK]

Hint: Use ~* for case-insensitive regex in nginx location [OK]

Common Mistakes:

• Using ~ instead of ~* for case-insensitive matching
• Confusing exact match (=) with regex
• Omitting regex operator for regex matching

3. Given this nginx config snippet:

location ~* \.jpg$ {
  return 200 'Image file matched';
}

What will be the response for a request to /photos/Sunset.JPG?

medium

A. 404 Not Found

B. 500 Internal Server Error

C. 200 with empty body

D. 200 with 'Image file matched'

Solution

1. Step 1: Analyze the regex and operator

   The ~* operator means case-insensitive regex match. The regex \.jpg$ matches strings ending with '.jpg' ignoring case.

2. Step 2: Check the request URL

   The request is /photos/Sunset.JPG, which ends with '.JPG' (uppercase). Case-insensitive match succeeds.

3. Final Answer:

   200 with 'Image file matched' -> Option D

4. Quick Check:

   Case-insensitive regex matches .JPG [OK]

Hint: ~* ignores case, so .JPG matches \.jpg$ regex [OK]

Common Mistakes:

• Assuming regex is case-sensitive with ~*
• Ignoring the $ end anchor in regex
• Confusing response codes returned

4. Identify the error in this nginx location block:

location ~* /images/(.*\.png$ {
  proxy_pass http://backend;
}

medium

A. Missing closing parenthesis in regex

B. Using ~* instead of ~ for case-sensitive match

C. proxy_pass URL is invalid

D. location block missing curly braces

Solution

1. Step 1: Check regex syntax

   The regex /images/(.*\.png$ has an opening parenthesis but no closing parenthesis.

2. Step 2: Validate other parts

   The ~* operator is valid for case-insensitive match, proxy_pass URL looks valid, and curly braces are present.

3. Final Answer:

   Missing closing parenthesis in regex -> Option A

4. Quick Check:

   Regex parentheses must be balanced [OK]

Hint: Count parentheses in regex to avoid syntax errors [OK]

Common Mistakes:

• Forgetting to close parentheses in regex
• Confusing ~ and ~* usage
• Ignoring syntax errors in regex patterns

5. You want to serve all URLs ending with .css or .CSS using a regex match in nginx. Which location block correctly matches both cases efficiently?

hard

A. location ~ \.css$ { }

B. location ~* \.css$ { }

C. location ~ \.css$|\.CSS$ { }

D. location ~* \.css$|\.CSS$ { }

Solution

1. Step 1: Understand case-insensitive matching

   Using ~* makes the regex case-insensitive, so it matches both '.css' and '.CSS'.

2. Step 2: Evaluate other options

   location ~ \.css$ { } uses case-sensitive ~, so it misses '.CSS'. Options C and D have incorrect regex syntax with unescaped pipes and redundant patterns.

3. Final Answer:

   location ~* \.css$ { } -> Option B

4. Quick Check:

   Use ~* for simple case-insensitive regex [OK]

Hint: Use ~* with simple regex to match case-insensitive extensions [OK]

Common Mistakes:

• Using ~ and missing uppercase matches
• Trying to match cases with complex regex instead of ~*
• Incorrect escaping of regex special characters