Getting Help at the Command Line

30 minutes
  • 3 Learning Objectives

About this Hands-on Lab

Linux systems have an average of 3,000 commands on them, so it’s not feasible to know more than a couple of hundred of the commands well. In this lab, we’ll discover how to find out more information about commands and files on the system.

Learning Objectives

Successfully complete this lab by achieving the following learning objectives:

Use Built-In Help and External Help Commands to Find Out More About a Given Command

Get help for a command

ls --help

Output the help to a file so it can be searched

ls --help > lshelp.txt

Scroll through the file:

less lshelp.txt

Quit out of it by hitting q.

Find out what will run with ls:

which ls

See if there are more on the system:

which -a ls

Find out more information about a command:

whereis ls

Find out what a command is:

whatis crontab
Use the `man` Command and Related Utilities to Find Out More Information on Desired Commands
man -f crontab

This will show us the sections.

man man

There will be a table that shows us the section numbers.
Quit out of it by hitting q.

man -f crontab

man 5 crontab

This takes us to the configuration file format of crontab.
Quit out of it by hitting q.

If we don’t know which one we want, enter:

man -a crontab

It will show us the first one.
Quit by hitting q.
if we want the next one. Hit Enter.

Investigate Additional Sources of Documentation on the System `tree`
cd /usr/share/doc/packages

Run the following:

tree -H '/usr/share/doc/packages' -L 1 --noreport --charset utf-8 > ~/packages_index.html

Note: If tree is not installed, you can install it by running sudo -i zypper in tree.

Additional Resources

You are a systems administrator just getting used to SUSE Linux Enterprise Server. Now, you are taking some time to find out more about the various commands on the system, using various utilities and the built-in command help.

Additionally, you discover a treasure trove of good documentation that's hard to access the way it's stored, so you will build an HTML index that helps navigate this information.

What are Hands-on Labs

Hands-on Labs are real environments created by industry experts to help you learn. These environments help you gain knowledge and experience, practice without compromising your system, test without risk, destroy without fear, and let you learn from your mistakes. Hands-on Labs: practice your skills before delivering in the real world.

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