Page 6 - Bash

Bash

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Signal Handling and Cleanup with trap

Maxim Mironjuk - December 18, 2025

When a shell script is terminated by Ctrl+C, kill or an error, lockfiles, temporary files and half-finished database operations are left behind unless signal handling is in place. The Bash builtin trap registers handlers for SIGINT, SIGTERM, SIGPIPE, ERR and EXIT, turning cleanup into a reliable, orderly process.

Bash Testing/E2E

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Testing Bash Scripts in Isolated Docker Containers

Maxim Mironjuk - December 07, 2025

A Bash script that runs cleanly on your own machine can fail on the target system because it runs a different coreutils version, is missing a tool, or ships a different Bash version. Docker test containers make these differences reproducibly visible and can be reused across the CI pipeline instead of being rebuilt from scratch on every run.

Bash Linux

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Build Terminal Dashboards for Log Analytics in Bash

Maxim Mironjuk - December 03, 2025

Not every team has Grafana or an ELK stack available when they need to know fast how many errors a service is producing right now. A Bash terminal dashboard built from watch, tput, and ANSI color codes shows error rates, request rates, and log levels live, right inside the SSH session, without a browser and without additional infrastructure.

Bash

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Getting stdin, stdout, and Interactive Tools Right

Maxim Mironjuk - December 02, 2025

Bash scripts that work correctly in a terminal often fail in pipes, as a cron job, or inside CI environments. The cause lies in how stdin, stdout, and interactive tools behave differently depending on context. /dev/null, /dev/tty, isatty detection, and non-interactive mode are the tools that make scripts work reliably in every context.

Bash Linux

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Sed: Multiline Substitutions with Hold Space and Pattern Space

Maxim Mironjuk - December 01, 2025

Anyone who only uses sed line by line with s/old/new/ quickly hits a wall with config blocks, XML fragments and multiline log entries. Hold space and pattern space give sed the ability to look at several lines at once and replace them as one connected block, without ever reaching for Perl or Python.

Bash Linux

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nohup vs. disown vs. setsid in Bash Explained for Background Services

Maxim Mironjuk - November 29, 2025

nohup ignores the SIGHUP signal, disown removes a job from the shell's job table after the fact, and setsid starts a brand-new session with no controlling terminal at all. Knowing the difference means picking the right, most robust tool for every background service in a deployment script.

Bash Linux

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Automating DNS Lookups with dig and host in Bash

Maxim Mironjuk - November 22, 2025

Anyone who only checks DNS records one at a time by hand misses propagation problems and silent changes. Automating DNS lookups with dig and host processes domain lists in seconds, compares resolvers, and catches configuration mistakes before customers report them.

Bash Linux

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S3 Sync Patterns with awscli in Bash Scripts: Deployment, Backup and Error Handling

Maxim Mironjuk - November 22, 2025

aws s3 sync transfers only changed files between a local directory and an S3 bucket, making it the standard tool for deployment and backup scripts in Bash. Used correctly it saves time and bandwidth. Used carelessly, the --delete flag can wipe out entire bucket contents in seconds. This article shows the patterns that make the difference.

Bash Security/OWASP

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SSH in Automation: known_hosts, Agent, Keys, and Security

Maxim Mironjuk - November 20, 2025

Using SSH correctly in automation scripts is trickier than it looks: disabling StrictHostKeyChecking solves the first connection problem, but it opens the door to man in the middle attacks. This article shows how SSH automation works without compromising security.

Bash

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Parsing INI Files in Pure Bash: Without External Tools

Maxim Mironjuk - November 15, 2025

Plenty of legacy tools and simple configuration files still use the INI format today: sections in square brackets, key-value pairs underneath. Bash ships with enough built-ins to read such a format reliably, as long as comments, whitespace, and quoting pitfalls are planned for from the start instead of patched in afterward.