Implement a formatted shell script output
Company: Amazon
Role: Software Engineer
Category: Coding & Algorithms
Difficulty: medium
Interview Round: Technical Screen
Write a shell script named script.sh that is invoked as: ./script.sh <username> <path_of_file>. It must print a single line formatted exactly as: <timestamp> <license> <user@hostname>. Use the supplied username and the current machine’s hostname, and parse the license value from the file at <path_of_file>. Include argument validation (missing args), file existence/permission checks, and clearly define the timestamp format you choose.
Quick Answer: This interview question evaluates algorithm design, data structures, correctness, complexity, edge cases, and implementation details in a realistic interview setting. A strong answer for Implement a formatted shell script output states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.
Solution
# Solution Alignment
The prompt asks for an implementation-level answer. The safest way to present it is to define the state, maintain clear invariants, then walk through complexity and tests.
## Problem Restatement
Write a shell script named script.sh that is invoked as: ./script.sh <username> <path_of_file>. It must print a single line formatted exactly as: <timestamp> <license> <user@hostname>. Use the supplied username and the current machine’s hostname, and parse the license value from the file at <path_of_file>. Include argument validation (missing args), file existence/permission checks, and clearly define the timestamp format you choose.
## Recommended Approach
Model each reachable configuration as a graph state and choose the traversal by edge cost: BFS for unweighted shortest paths, Dijkstra for non-negative weighted paths, or topological DP for DAGs. Track visited states at the correct granularity so cycles do not cause repeated work.
## Correctness
The implementation should maintain an invariant after each loop or operation that directly matches the problem statement. At termination, that invariant implies the returned value has considered every valid candidate exactly once, or has preserved the required data-structure state after every API call.
## Complexity
BFS is O(V + E) time and O(V) space for a standard graph. Expanded-state problems multiply those bounds by the number of state dimensions.
## Edge Cases and Tests
Disconnected graph, source equals target, cycles, duplicate edges, unreachable target, and whether the answer counts nodes, edges, moves, or transfers.