Master Linux Command Basics: Usage, Locations, and Help Retrieval

1. Linux command usage format

Linux commands follow a specific syntax: command [options] [arguments]. Options modify command behavior, while arguments specify targets or inputs.

2. Linux system program file locations

Executable program files are typically stored in directories such as /bin, /usr/bin, /sbin, and /usr/sbin. Libraries reside in /lib or /usr/lib, and configuration files are often found under /etc.

3. Linux get command help information

Distinguishing internal and external commands

Internal commands are loaded into memory at system startup and run efficiently, while external commands are separate executable files loaded from disk when needed.

Getting help for internal commands

Use #help COMMAND to display built‑in help.

Getting help for external commands

Manual page: #man COMMAND (files located in /usr/share/man)

Short help options: #COMMAND --help or #COMMAND -h Info pages: #info COMMAND Program documentation files: README, INSTALL, ChangeLog

Official documentation directories: Documentation, vendor docs

Search online (e.g., Google)

Man page sections

The manual is divided into sections such as:

Executable commands and files

System calls and kernel interfaces

Library functions (mostly C library)

Device file specifications (usually under /dev)

File formats and configuration files

Games

Conventions and standards (e.g., file system layout, network protocols, ASCII)

System administration commands

Kernel‑related files (post‑CentOS 7)

Understanding these sections helps users locate the information they need quickly.