Investigate service failures
systemctl · journalctl · ss · 10 posts
Detecting Bash Script Failures with strict mode and trap
Learn how to reliably detect Bash script failures with errexit, nounset, pipefail, and ERR/EXIT traps, including safe execution with exception handling and cleanup.
Linux · ProgrammingManage Process Limits with limits.conf and systemd
This guide explains how to set nofile and nproc limits using limits.conf and systemd settings such as LimitNOFILE, and how to verify the effective values in different execution contexts for shells and services.
Linux · System AdministrationDesigning systemd Unit Dependencies and Startup Order
This guide explains how to design dependencies and startup order between systemd Units using Wants, Requires, After, Before, and targets, and how to verify their behavior on an actual system when failures occur.
Linux · System Administrationsystemd-journald Persistence, Capacity Limits, and Rotation
This guide explains how to configure log persistence, capacity limits, and rotation using systemd-journald settings such as Storage, SystemMaxUse, and vacuum, and how to verify that logs are retained after a reboot.
Linux · System AdministrationCPU, Memory, and IO Limits for systemd Services
This article explains how to set per-service resource limits using systemd settings such as CPUQuota, MemoryMax, and TasksMax, and how to verify their effective values and behavior when the limits are reached.
Linux · System AdministrationConfiguring and Troubleshooting Linux Time Synchronization with chrony
This article explains how to configure Linux time synchronization with chrony, verify synchronization status with sources and tracking, use waitsync, persist the configuration, and isolate the causes of time drift by checking reachability.
Linux · System AdministrationInvestigating Listening Ports and Connection States with the ss Command
This article explains how to use the ss command to check listening ports, associated processes, TCP states, and filter conditions, and how to troubleshoot port conflicts and connection failures from the server side.
Linux · NetworkingLinux Log Investigation and Retention Management with journalctl and systemd-journald
This guide systematically explains how to search and investigate Linux logs and manage persistence, capacity control, and retention with journalctl and systemd-journald.
Linux · System AdministrationPractical Guide to systemd Service Management and Unit Files
A practical guide to service management with systemd, Unit file design, dependencies, automatic startup, restart on failure, safe configuration changes with drop-ins, and verification methods.
Linux · System AdministrationWindows Network Diagnosis Tools Guide
Practical examples for resolving communication issues in Windows Server using ping, tracert, netstat, and Get-NetTCPConnection.
Windows Server