Explainer
Copy files and directory trees in Python
Use shutil.copy, copy2, and copytree, understand metadata limits and overwrites, and handle errors without treating a file copy as a complete backup.
Explainer
Fix a Postfix Relay access denied error safely
Identify whether a message needs local delivery, authenticated submission, or a permitted relay destination before changing Postfix access rules.
Explainer
Collect a text log with rsyslog’s imfile module
Read text files with imfile, persist offsets, combine multiline events, and distinguish rotation handling from first-start behavior.
Explainer
Pause execution in Python with sleep
Use time.sleep in synchronous code and asyncio.sleep in coroutines, with clear limits for timing accuracy, thread behavior, and recurring schedules.
Technical guide
Create a directory if it does not exist in Node.js
Use recursive mkdir to create missing parents and accept an existing directory, while still handling permission and path conflicts.
Technical guide
Create a .gitignore file
Write and share Git ignore rules, check which patterns match, and keep exceptions working without accidentally treating inline comments as patterns.
Explainer
Route Logstash events to multiple Elasticsearch indices
Set an internal index prefix, provide a fallback for every event, and distinguish daily indices from ILM rollover and data streams.
Explainer
Create nested directories in Python
Create missing parent directories with pathlib or os.makedirs, tolerate existing directories, and understand permissions, races, and path conflicts.
Explainer
Build a Python dictionary from two lists
Combine keys and values with dict and zip, reject mismatched lengths, handle duplicate keys, and avoid unexpected keys when filling missing values.
Technical guide
Create a remote Git branch
Publish a local branch with tracking, create a branch from an existing remote-tracking ref, and verify the result without confusing local and server state.
Explainer
Implement a singleton in Python
Compare module-level instances, metaclass caching, and __new__ in Python, including repeated initialization, thread safety, and testing trade-offs.
Explainer
Troubleshoot a Logstash file input that is not reading
Check discovery, permissions, sincedb state, line endings, and rotation before replaying a file or changing its tracking state.