version: 1
id: linux-navigation
title: Linux Navigation and Permissions
summary: Repair a deployment workspace using paths, ownership, modes, and pipelines.
difficulty: beginner
estimatedMinutes: 20
prerequisites: []
image: alpine:3.21
shell: /bin/sh
setup:
  - mkdir -p /workspace/releases /workspace/logs
  - printf '#!/bin/sh\necho deployed\n' > /workspace/releases/deploy.sh
  - chmod 0644 /workspace/releases/deploy.sh
  - printf 'INFO ready\nERROR disk\nERROR timeout\n' > /workspace/logs/app.log
tasks:
  - id: executable
    title: Restore the deployment command
    description: Make releases/deploy.sh executable without making it writable by everyone.
    hints:
      - Inspect the current mode with ls -l.
      - chmod 755 grants execute while limiting writes to the owner.
    checks:
      - type: command
        name: Deployment script is executable
        command: test -x /workspace/releases/deploy.sh
      - type: command
        name: Deployment script is not world-writable
        command: test "$(stat -c %a /workspace/releases/deploy.sh)" = 755
  - id: pipeline
    title: Extract incident signals
    description: Use a pipeline to write only ERROR lines to /workspace/errors.txt.
    hints:
      - grep can select lines by a fixed word.
    checks:
      - type: file
        name: Error report exists
        path: /workspace/errors.txt
        value: ERROR disk
      - type: command
        name: Error report has two lines
        command: test "$(wc -l < /workspace/errors.txt)" -eq 2
limits: {cpus: "0.5", memory: 128m, pids: 64, timeout: 1800, network: false}