Linux Commands
Command references for core Linux tools, syntax, examples, and practical one-liners.
How to Truncate Files in Linux: Empty Files Without Deleting
Empty a file without deleting it using shell redirection or the truncate command. Covers permissions, sudo workarounds, and truncating log files.
How to Use the Linux ftp Command to Transfer Files
Transfer files to and from a remote server using the Linux ftp command. Covers connections, downloads, uploads, passive mode, and binary transfers.
lsmod Command in Linux: List Kernel Modules
Display all currently loaded Linux kernel modules with lsmod. This guide covers output format, filtering, and related module management commands.
rename Command in Linux: Rename Multiple Files
Batch rename files in Linux with the rename command using Perl regular expressions. Includes syntax, examples, and tips for the Perl and C versions.
ss Command in Linux: Display Socket Statistics
The ss command displays socket statistics and open ports and is the modern replacement for netstat. This guide explains how to list TCP, UDP, and Unix sockets, filter by port and state, and identify which process owns a socket.
pgrep Command in Linux: Find and Filter Running Processes
The pgrep command finds running processes by regex pattern, user, terminal, or parent PID and prints matching PIDs. This guide covers exact matching, filtering options, and script-friendly exit checks.
unlink Command in Linux: Remove a Single File
The unlink command removes a single file by deleting its directory entry. This guide explains how to use unlink, how it differs from rm, and what to expect when removing files and symbolic links.
uniq Command in Linux: Remove and Count Duplicate Lines
The uniq command removes or counts duplicate adjacent lines in a file. This guide explains how to filter duplicates, count occurrences, and use uniq with sort in pipelines.
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.
head Command in Linux: Display the First Lines of a File
The head command prints the first lines or bytes of one or more files. Learn how to use head to preview files, limit pipeline output, and inspect logs.
ssh Command in Linux: Connect to Remote Servers
Connect to remote servers securely using the ssh command. Covers basic connections, key-based authentication, SSH config files, running remote commands, port forwarding, and troubleshooting.
Check Open Ports in Linux: nmap, netcat, and Bash
Three ways to check which ports are open on a Linux system from the command line: nmap, netcat, and the Bash /dev/tcp pseudo-device.
ifconfig Command in Linux: Configure Network Interfaces
Configure and view network interfaces in Linux using ifconfig. Covers IP assignment, enabling and disabling interfaces, MTU, MAC address changes, and modern ip command equivalents.
groupdel Command in Linux: Delete a Group
Learn how to delete a Linux group using the groupdel command. Covers syntax, verification, handling primary group errors, and what happens to files owned by the deleted group.
wc Command in Linux: Count Lines, Words, and Bytes
The wc command counts lines, words, characters, and bytes in files or standard input. This guide covers all options with practical pipeline examples.
top Command in Linux: Monitor Processes in Real Time
The top command displays running processes and system resource usage in real time. This guide covers sorting, filtering, load metrics, and key interactive controls.
usermod Command in Linux: Modify User Accounts and Groups
The usermod command modifies user account attributes such as groups, shell, home directory, username, and expiry date. This guide covers all common options with examples.
sort Command in Linux: Sort Lines of Text
The sort command sorts lines of text files alphabetically or numerically. This guide covers sorting by column, reverse order, unique lines, and combining sort with other commands.
wall Command in Linux: Broadcast Messages to Logged-In Users
The wall command broadcasts a message to the terminals of all logged-in users in Linux. This guide covers sending messages from arguments, files, and pipes, with group targeting and banner control.
journalctl Command in Linux: Query and Filter System Logs
journalctl queries the systemd journal and lets you filter logs by unit, time, priority, boot, and process. This guide covers the most useful journalctl options with practical examples.
