Linux Commands #2 : Getting Help

Getting Help

The Operating System (OS) and the "man" Command

An operating system (OS) is a critical software program that facilitates communication between computer hardware and software. Key functions of an OS include:

• Managing the distribution of internal memory among applications
• Overseeing input/output operations for connected hardware devices
• Communicating operational statuses and error messages
• Delegating the management of batch jobs (e.g., printing)
• Dividing programs to run across multiple processors simultaneously in parallel processing environments

Examples of popular computer operating systems include Red Hat Linux, Microsoft Windows, Apple macOS, Ubuntu Linux, Google Android, and iOS.

The "man" Command : 

• The "man" command provides access to an online manual that potentially contains a complete description of every command available on the system.
• It can also provide one-line descriptions of commands that match a specified keyword.
• The online manual is divided into sections:

►  - 1. User Commands

►  - 2. System Commands

► - 3. Subroutines

► - 4. Devices

►  - 5. File Formats

►  - 6. Games

►  - 7. Miscellaneous

►  - 8. System Administration

►  - l. Local Commands

►  - n. New Commands

Examples of using the "man" command:

•    To display the manual page for the "cp" (copy files) command: `man cp`
•    To access a different section, specify the section: `man 8 telnetd`
•    Keyword searching: `man -k mail` or `man -k 'copy files'`
•    To view a one-line description of a command: `whatis more`

To view a one line description of what a command does: 

• whatis more

will display what the "more" command does:

more, page (1) - browse or page through a text file

 ► who - shows who is on the system

• who
• whoami

 ►finger - displays information about users, by name or login name finger doe

• finger userid