Page 15 - Bash

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Measuring and Improving Code Coverage for Bash Scripts

Maxim Mironjuk - February 23, 2025

Having a bats test suite for Bash scripts tells you nothing about which lines are actually executed. Code coverage with kcov closes that gap, shows line by line what tests really cover, and makes untested error paths visible long before they become a problem in production.

Bash

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Bash for Backups: Rotating Snapshots and Restore Tests

Maxim Mironjuk - February 20, 2025

A backup that has never been tested is just a hypothesis. Bash backup scripts that combine rsync for incremental snapshots with tar for archived copies, clean up rotating backups according to a configurable retention policy, and run restore tests automatically make the difference between a data protection routine and a verified recovery process.

Bash Linux

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Generate HTML Reports Directly From Bash

Maxim Mironjuk - February 19, 2025

A cron job that runs overnight has to deliver a readable result by morning. Instead of scrolling through a log file, a Bash report builds a finished HTML page with tables, bars, and status badges directly, ready to send by mail or drop on an internal server, without PHP, Python, or a templating library.

Bash

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jq for JSON in Everyday Shell Work: Filter, Transform, Validate

Maxim Mironjuk - February 12, 2025

jq makes JSON in the shell first class. Once you master filters, select(), map(), has(), and type checks, pass variables safely with --arg, and handle errors with try/catch, you can process API responses, config files, and log data directly in Bash, with no detour through Python or Node.

Bash

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Using Arrays in Bash Instead of String Hacks

Maxim Mironjuk - February 11, 2025

String hacks in Bash, file lists as whitespace-separated strings, configuration values as comma-separated fields, break systematically as soon as a value contains a special character. Arrays in Bash are the clean alternative: indexed arrays for ordered lists, associative arrays for key-value structures, slices for subsets and safe iteration for every use case.

Bash Security/OWASP

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Restricted Shell (rbash) in Bash: Using Limited Environments Correctly

Maxim Mironjuk - February 11, 2025

The restricted shell rbash blocks cd, PATH changes, and calling programs through a path containing a slash. That is enough for simple, benign restrictions like an SFTP replacement, but it can be bypassed with documented techniques relatively easily. Anyone using rbash should know exactly what it covers and what needs additional hardening.

Bash Docker

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BusyBox ash Limits in Alpine Containers and How to Work Around Them

Maxim Mironjuk - February 08, 2025

An entrypoint script with arrays and process substitution runs fine locally and fails inside an Alpine container with exec format error. The reason is BusyBox ash, which serves as /bin/sh in the default Alpine image instead of Bash and offers only a fraction of the familiar feature set.

Bash Linux

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Tr: Practical Everyday Use Cases in the Shell

Maxim Mironjuk - January 31, 2025

tr is often seen as the simplest text tool in the shell and gets underrated because of it. Character classes, targeted deletion with -d and squeeze with -s make tr the fastest tool for input normalization, delimiter swapping and cleaning up control characters, often quicker to type and quicker to run than an equivalent sed command.

Bash

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Writing Scripts That Work in Both Bash and zsh

Maxim Mironjuk - January 28, 2025

Since macOS Catalina, zsh has been the default login shell, while servers and CI environments keep relying on Bash. Anyone writing a script or a dotfile function meant for both shells has to know array indices, globbing and option names that differ fundamentally.

Bash

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Processing Logs in Bash: grep, awk, sed and jq Working Together

Maxim Mironjuk - January 25, 2025

Processing logs in Bash means more than running grep and eyeballing the output. Time window filtering, structured error reporting, frequency analysis and combining grep, awk, sed and jq into efficient pipelines make the difference between reactive troubleshooting and proactive log monitoring.