Linux Commands
Command references for core Linux tools, syntax, examples, and practical one-liners.
tail Command in Linux: Show Last Lines and Follow Logs
Use the Linux tail command to show the last N lines or bytes of a file, follow logs in real time with tail -f, and filter live output with grep.
umask Command in Linux: Set Default File Permissions
The umask command sets the default permission mask for newly created files and directories. This guide explains how umask works, how to calculate its value, and how to make it permanent.
export Command in Linux: Set Bash Environment Variables
Use export to turn Bash shell variables into environment variables that child processes inherit, list exported variables, and make them permanent across sessions.
lsof Command in Linux: Find Open Files and What Is Using a Port
Use the lsof command to find what is using a port, identify processes holding files open, and locate deleted files that still consume disk space.
How to Unzip a .gz File in Linux
Unzip a .gz file in Linux with gzip or gunzip, keep the original file when needed, and extract .tar.gz archives with tar.
sha256sum and md5sum: Verify Checksums in Linux
Check a file's SHA-256 or MD5 checksum in Linux: generate digests with sha256sum and md5sum, verify SHA256SUMS lists with -c, and confirm ISO downloads.
What Is stdin, stdout, and stderr in Linux
stdin, stdout, and stderr are Linux's three standard streams. See how file descriptors 0, 1, and 2 connect commands to terminals, files, and pipes.
less Command in Linux: Navigate and Search Files
How to use the less command in Linux to view files page by page, search for text, follow log files in real time, and navigate with vi-style key bindings.
passwd Command in Linux: Change User Passwords
Change your own, another user's, or the root password in Linux with the passwd command. Covers password expiry with chage, forcing a change at next login, and account locking.
tree Command in Linux: Display Directory Structure
The tree command lists directories recursively as an indented tree. This guide covers installation, depth limits, filtering, sizes, and saving the output.
curl Command in Linux: Usage and Examples
The curl command transfers data to and from servers using HTTP, HTTPS, FTP, and other protocols. This guide covers downloads, headers, POST requests, verbose debugging, proxies, and API usage.
nohup Command in Linux: Background Jobs and Output
nohup keeps commands running after logout. The 'appending output to nohup.out' message is not an error. This guide covers background jobs, 2>&1 redirection, and stopping processes.
tmux Command in Linux: Sessions, Windows, and Panes
The tmux command lets you run persistent terminal sessions with multiple windows and panes. This guide covers creating and managing sessions, splitting panes, copy mode, and configuration.
strace Command in Linux: Trace System Calls
Use the strace command to trace system calls and signals on Linux, debug why a program fails, find missing files, and measure where a process spends its time.
How to Manage Node.js Processes with PM2
How to install PM2, run and manage Node.js processes with clustering, zero-downtime reloads, log rotation, and systemd integration that survives reboots.
htop Command in Linux: How to Monitor and Manage Processes
Monitor Linux processes in real time with htop: read CPU and memory meters, sort and filter the process list, and kill or renice processes from one screen.
smartctl Command in Linux: Check Disk Health with SMART
Use smartctl in Linux to check SMART health, read disk attributes, run self-tests, troubleshoot USB enclosures, and monitor NVMe wear.
find Command in Linux: Search Files and Directories
The find command searches for files and directories by name, type, size, date, permissions, and more. This guide covers practical examples including wildcards, exec actions, and combining find with grep.
How to Create a Directory in Linux: mkdir Command Examples
Create single, multiple, and nested directories in Linux with mkdir, set permissions with -m, and fix 'Permission denied' and 'No such file or directory' errors.
ffmpeg Command in Linux: Convert, Compress, and Extract Media
Practical ffmpeg examples for converting between formats, compressing video with CRF, extracting audio, trimming clips, resizing video, and batch processing files on Linux.
