Identifying which ports a specific process is using comes up regularly in debugging, security audits, and infrastructure management. Here are the practical methods. Using ss The ss command is the modern standard for socket inspection: ss -tlnp | grep <PID> This shows listening TCP sockets (-t for TCP, -l for listening). Add -u if you…
Use ipcs to see all IPC resources on your system: ipcs -m This shows System V shared memory segments with details like: SHMID: The segment identifier OWNER: User who created it PERMS: Permissions (octal format) BYTES: Size in bytes NATTCH: Number of processes attached For a more compact view focused on just what you need:…
Storage Limitations BIOS uses MBR (Master Boot Record) partitioning, which maxes out at 2.2TB addressable space due to 32-bit LBA limitations. UEFI uses GPT (GUID Partition Table), supporting drives up to 9.4 zettabytes theoretically—practically unlimited for current hardware. If you’re deploying systems with large storage arrays or NVMe drives, UEFI is mandatory. Boot Process UEFI…
If you’re getting this error when running bibtex on your auxiliary file, it typically means your document has no citations, even though BibTeX is being invoked: This is BibTeX, Version 0.99d (TeX Live 2015/Debian) The top-level auxiliary file: main.aux The style file: latex8.bst I found no citation commands—while reading file main.aux (There was 1 error…
SMP (Symmetric Multiprocessing) and NUMA (Non-Uniform Memory Access) represent two fundamentally different approaches to multi-processor system architecture. Understanding the distinction matters because it affects how you tune applications, configure kernel parameters, and optimize workloads. Memory Access Latency In SMP, all processors have equal latency when accessing any memory location. Every CPU communicates with RAM through…
Retrieving hardware serial numbers is essential for inventory management, warranty tracking, and identifying physical servers across your infrastructure. The standard approach uses dmidecode, which reads the system’s DMI (Desktop Management Interface) data. Using dmidecode First, install the tool: sudo apt-get install dmidecode For Rocky Linux, RHEL, and derivatives: sudo dnf install dmidecode Then query the…
Password-less SSH login is faster, more secure, and essential for automation. Combining it with remote command execution lets you run tasks on servers from your local machine without interactive authentication. Setting Up SSH Key-Based Authentication Generate SSH Keys First, generate an ED25519 key pair on your local machine (A): ssh-keygen -t ed25519 -C “user@hostname” -f…
The classic LaTeX workflow requires running pdflatex multiple times with BibTeX in between: pdflatex main.tex bibtex main pdflatex main.tex pdflatex main.tex This seems redundant, but there’s a solid reason for it. How the Three-Pass Workflow Works First LaTeX pass: LaTeX processes your document and writes all \cite{} commands to the .aux file. At this point,…
You need to detect whether STDERR (file descriptor 2) is connected to a terminal or redirected to a file or pipe. This is useful for conditional logging, color output, or error handling that depends on the output destination. Using file descriptor tests The primary method is the -t test operator, which checks if a file…
I/O schedulers in Linux sit between application requests and physical disk hardware, deciding the order in which I/O operations execute. The fundamental difference between work-conserving and non-work-conserving schedulers comes down to how they handle idle periods. Work-Conserving Schedulers A work-conserving scheduler must dispatch a pending I/O request whenever one exists, regardless of physical disk positioning….
Accurate system time is critical for log timestamps, security operations, certificate validation, and coordinating across distributed systems. Modern Linux distributions handle time synchronization automatically, but you’ll occasionally need to set the time manually. Using timedatectl The standard tool for time management on systemd systems is timedatectl. Check your current time and synchronization status: timedatectl status…
The diff command on Linux is standard, but Windows doesn’t ship with an equivalent by default. You have several solid options depending on whether you prefer command-line or GUI tools. Command-Line Alternatives If you want a command-line experience similar to Linux diff: Windows PowerShell (built-in, Windows 10+): Compare-Object (Get-Content file1.txt) (Get-Content file2.txt) For more diff-like…
Python’s str.split() method splits a string by a separator and returns a list. Here are the common patterns: “a string separated by space”.split() # [‘a’, ‘string’, ‘separated’, ‘by’, ‘space’] “a,string,separated,by,comma”.split(“,”) # [‘a’, ‘string’, ‘separated’, ‘by’, ‘comma’] Note that calling split() without arguments splits on any whitespace and automatically removes empty strings. Handling consecutive separators When…
When you call os.makedirs(path, mode=0o777) in Python, the resulting directory often won’t have the permissions you expect. The mode argument gets masked by the process’s umask, which removes certain permission bits before applying them to the filesystem. Your umask acts as a filter. If your umask is 0o022 (common on many systems), it removes write…
When you access a non-existent key in a Python dictionary, you’ll hit a KeyError. There are several approaches to handle this gracefully depending on your use case. The .get() Method The simplest and most common approach: value = my_dict.get(‘key’, ‘default_value’) This returns the value if the key exists, or the default value if it doesn’t….
GNOME 3 and GNOME Classic don’t provide built-in autohide functionality for the top panel or taskbar. Unlike some lightweight desktop environments, this feature isn’t available through the standard settings or extensions in recent GNOME versions. If you need panels that automatically hide when applications are running, you have several options: GNOME Extensions (limited approach) While…
alien is a straightforward package converter available in EPEL that handles conversion between .deb, .rpm, Slackware, and other package formats. This is useful when you need to install Debian packages on RPM-based systems. Prerequisites You need EPEL (Extra Packages for Enterprise Linux) enabled. On CentOS 7, 8, or Rocky Linux 8+: sudo dnf install epel-release…
Interrupts are fundamental to how your Linux system handles hardware and software events. Monitoring them in real-time helps identify performance bottlenecks, device driver issues, and CPU load imbalances. Here’s how to check interrupts effectively. Quick Live Monitoring with /proc/interrupts The simplest approach is reading /proc/interrupts directly: cat /proc/interrupts This shows a snapshot of interrupt counts…
Filesystem corruption occasionally happens. When it does, you need fsck to run before the system fully mounts its filesystems. Here’s how to force a filesystem check during the next boot. Using touch to Mark Filesystems The traditional method is to create /forcefsck: sudo touch /forcefsck sudo reboot On the next boot, the system will check…
The NameNode in HDFS maintains the filesystem namespace in memory. The Secondary NameNode (or Checkpoint Node in HA setups) periodically merges the namespace image (fsimage) with the edit logs to create a new checkpoint. Understanding how to force this process is essential for cluster maintenance and recovery operations. How Checkpointing Works The checkpoint process combines…