Command Output Logging

When to use this skill

Use it whenever running commands that:

• •are slow or long-running or expensive in any way
• •are likely to need multiple analyses of their output
• •involve API calls or other network operations
• •are GitHub CLI commands (gh) or similar

How it works

Always pipe these commands through tee(1) to capture output to a file while still displaying it in real-time.

Key Principles

• •

  Never blindly pipe through head(1) unless you're sure premature termination via SIGPIPE won't cause problems.

• •

  When tee-ing into a temporary logfile, prefer the tmp/ subdirectory of the repository rather than /tmp, so that you don't have to ask permission for access to /tmp.

• •

  Don't assume tmp/ exists - you might need to create it first.

Usage

1. •

   Create tmp/ directory if it doesn't exist: mkdir -p tmp/

2. •

   Run the command with tee: command | tee tmp/output.log

3. •

   The user can now choose to monitor that log file as it runs.

4. •

   If you subsequently need to examine the output multiple times, reading from the log file prevents needing to re-run the slow command each time.

Examples

# Run tests with logging
mkdir -p tmp/
npm test | tee tmp/test-output.log

# Check GitHub action run
mkdir -p tmp/
gh run view 12345 | tee tmp/action-run-12345.log

# Access some API
mkdir -p tmp/
some-API-call-command | tee tmp/logs.log