Uptime Crew·Software Engineer·Technical Phone Screen·Intermediate

Intermediate

May 2026

Summary

Technical screen at Uptime Crew for a Software Engineer role, focused entirely on shell scripting and numeric processing. Pretty niche stuff, not the usual leetcode grind.

Questions Asked (1)

Write a bash one-liner or short script that reads from a file or stdin, pulls out all numeric values (integers, decimals, negatives), and prints their sum.

Technical Trade-offsAlgorithms & Data Structures

Author's notes

I went straight for grep piped into awk, which worked for the basic case.

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Suggested Approach

Start by clarifying requirements: what counts as a numeric value (e.g., integers, decimals, negatives, scientific notation), whether to handle multiple numbers per line, and whether to read from stdin or a file. Then present a concise solution using grep with a regex to extract numbers and awk to sum them, explaining each part. Finally, discuss edge cases and trade-offs, such as performance on large inputs and handling of malformed numbers.

Pro tip: Mention that using `grep -oE` with a robust regex like `-?[0-9]+(\.[0-9]+)?` avoids partial matches and that `awk` can sum directly without a separate `paste` or `bc` loop, which is more efficient. Also, note that you can use `awk` alone to both extract and sum, but a pipeline is often clearer.

1. Clarify requirements and assumptions

Ask or state assumptions about what constitutes a numeric value (e.g., integers, decimals, negatives, scientific notation), whether numbers can appear multiple per line, and whether input is from stdin or a file. This shows attention to detail and avoids ambiguity.

2. Choose the right tools

Select `grep` for extraction and `awk` for summation, or use `awk` alone. Explain why these tools are appropriate: `grep -oE` efficiently extracts all matches, and `awk` handles floating-point arithmetic and can sum in one pass.

3. Construct the command

Write the one-liner: `grep -oE -- '-?[0-9]+(\.[0-9]+)?' file | awk '{s+=$1} END {print s}'`. For stdin, omit the file argument. Explain each part: `-o` prints only matches, `-E` enables extended regex, and `awk` accumulates the sum.

4. Test and validate

Test with sample inputs including edge cases: negative numbers, decimals, numbers attached to text (e.g., 'abc-12.3def'), and empty input. Show that the command handles them correctly and discuss any limitations (e.g., scientific notation not matched).

5. Discuss trade-offs and alternatives

Mention alternative approaches (e.g., using `sed` or `perl`) and trade-offs: regex complexity vs. performance, portability across systems, and handling of very large files. Emphasize that the chosen solution balances readability and efficiency.

Key Points to Mention

Use of `grep -oE` with a regex that matches integers, decimals, and negatives: `-?[0-9]+(\.[0-9]+)?`
Piping to `awk` for summation, which handles floating-point numbers and avoids external dependencies like `bc`
Handling multiple numbers per line and numbers embedded in text (e.g., 'abc-12.3def')
Edge cases: empty input, no numbers, very large numbers, and scientific notation (if relevant)
Performance considerations: `grep` and `awk` are efficient for large files, but regex complexity can impact speed
Portability: the solution works on most Unix-like systems, but `grep -E` may differ slightly (e.g., BSD vs. GNU)

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.