Thursday, April 24, 2025

During testing phase - Errors & logs observed

 A segmentation fault occurs when a program attempts to access a memory location that it is not allowed to access, or attempts to access a memory location in a way that is not allowed (for example, attempting to write to a read-only location, or to overwrite part of the operating system)

A "Memory access fault by GPU node-15" error usually indicates a problem where a program is trying to access memory that either doesn't exist or is not accessible to it, often related to the GPUThis can be due to various reasons, including memory errors, incorrect code, or issues with the GPU drivers or the application itself

hardware-related issues debugging purpose,  below logs will be useful:

 kern.log/ syslog/ dmesg / dpkg

All the above logs are present in this (cd /var/log/) location

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kern.log is a system log file found on Linux-based os (like Ubuntu, Debian, etc.)

Path: /var/log/kern.log 

What kern.log contains

        • Kernel-related messages (e.g., module loading, device detection)

        • Hardware driver activity

        • I/O operations

        • Warnings or errors from kernel-level processes

When to Check kern.log

• System crashes or freezes

• Troubleshooting hardware (USB, disk, network cards)

• Investigating kernel panics or driver issues

Command for Search errors: grep -i error /var/log/kern.log   

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syslog is a system log file that captures a wide variety of system-related messages, including:

• System processes
• Daemons
• Network services
• Cron jobs
• Kernel (sometimes, depending on the distro)

What syslog contains
• System service startup/shutdown logs
• Networking events (like DHCP, firewall)
• Scheduled task output (cron jobs)
• General system messages from daemons (e.g., sshd, systemd, NetworkManager)
• Occasionally includes kernel messages (unless separated into kern.log)

Practical Use Cases of syslog
• Debugging boot issues
• Monitoring SSH login attempts
• Tracking cron job execution
• Detecting misbehaving services
• Network issues or time synchronization problems (e.g., ntpd)

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Sunday, April 13, 2025

Testing Basics book by Narendra Boyina

Error: We can say that a mistake was made by a programmer during coding. (dev)

Defect: An error found during unit testing in the development phase. (dev)

Bug: An error was found during the testing phase. (QA)

Failure: an error found at the end-user.