Core Linux Commands

Common commands are easier to remember when grouped by discovery, inspection, navigation, and search.

Overview

Command	Purpose
`man`	Read manual pages
`apropos`	Search manual page descriptions by keyword
`explainshell`	External reference for command syntax

Command	Purpose
`whoami`	Print the current user
`id`	Show user and group IDs
`hostname`	Get or set the hostname
`uname`	Show kernel and system information
`pwd`	Print the current directory
`env`	Show or set environment variables
`ps`	Inspect processes
`who`	Show logged-in users
`lsof`	Show open files
`lsblk`	List block devices
`lsusb`	List USB devices
`lspci`	List PCI devices

Command	Purpose
`ifconfig`	Legacy network interface tool
`ip`	Modern network interface tool
`netstat`	Legacy network status tool
`ss`	Inspect sockets

Command	Purpose
`ls`	List directory contents
`cd`	Change directory
`which`	Show the executable path for a command

ls -l /etc
which python

ls -a includes hidden files. cd - returns to the previous directory.

find / -type f -name "*.conf" -user root -size +20k -newermt 2020-03-03 -exec ls -al {} \; 2>/dev/null
locate "*.conf"
sudo updatedb

Option	Purpose
`-type f`	Search for files
`-name "*.conf"`	Match a filename pattern
`-user root`	Filter by owner
`-size +20k`	Match files larger than 20 KiB
`-newermt DATE`	Match files modified after a date
`-exec ... {}`	Run a command for each result

Tool	Strength
`find`	Real-time, flexible, slower
`locate`	Indexed, fast, may be stale