Linux For Dummies Cheat Sheet

From Linux For Dummies, 9th Edition

By Richard Blum

As an alternative to more widespread operating system, open-source Linux is a little different, but that doesn’t mean you can’t do normal things, such as playing DVDs with it. You may need to get familiar with the Linux commands, but Linux offers easy ways to find help.

Common Linux Commands

Open-source Linux is a popular alternative to Microsoft Windows, and if you choose to use this low-cost or free operating system, you need to know some basic Linux commands to configure, operate, and interact with your system smoothly.
When dealing with the Linux operating system, commands are required as inputs to inform or direct a computer program to perform a specific operation. Understanding the most basic Linux commands will allow you to successfully navigate directories, manipulate files, change permissions, display information such as disk space, and more. Obtaining basic knowledge of the most common commands will help you easily execute tasks via the command line.
Find the most common Linux commands in this table:

Linux Commands

Command	Description
cat [filename]	Display file’s contents to the standard output device (usually your monitor).
cd /directorypath	Change to directory.
chmod [options] mode filename	Change a file’s permissions.
chown [options] filename	Change who owns a file.
clear	Clear a command line screen/window for a fresh start.
cp [options] source destination	Copy files and directories.
date [options]	Display or set the system date and time.
df [options]	Display used and available disk space.
du [options]	Show how much space each file takes up.
file [options] filename	Determine what type of data is within a file.
find [pathname] [expression]	Search for files matching a provided pattern.
grep [options] pattern [filesname]	Search files or output for a particular pattern.
kill [options] pid	Stop a process. If the process refuses to stop, use kill -9 pid.
less [options] [filename]	View the contents of a file one page at a time.
ln [options] source [destination]	Create a shortcut.
locate filename	Search a copy of your filesystem for the specified filename.
lpr [options]	Send a print job.
ls [options]	List directory contents.
man [command]	Display the help information for the specified command.
mkdir [options] directory	Create a new directory.
mv [options] source destination	Rename or move file(s) or directories.
passwd [name [password]]	Change the password or allow (for the system administrator) to change any password.
ps [options]	Display a snapshot of the currently running processes.
pwd	Display the pathname for the current directory.
rm [options] directory	Remove (delete) file(s) and/or directories.
rmdir [options] directory	Delete empty directories.
ssh [options] user@machine	Remotely log in to another Linux machine, over the network. Leave an ssh session by typing exit.
su [options] [user [arguments]]	Switch to another user account.
tail [options] [filename]	Display the last n lines of a file (the default is 10).
tar [options] filename	Store and extract files from a tarfile (.tar) or tarball (.tar.gz or .tgz).
top	Displays the resources being used on your system. Press q to exit.
touch filename	Create an empty file with the specified name.
who [options]	Display who is logged on.

How to Use CDs and DVDs with Linux

Just because you’re using open-source Linux as your operating system is no reason to think you can’t play CDs or watch DVDs on your computer. To access or remove disks, just follow these procedures:
To access your CDs/DVDs:

• If you’re in the GUI, the media should be automatically detected.
• On the command line, start by typing mount /media/cdrom. If this doesn’t work, look in the /media directory. You may need to use /media/cdrecorder, /media/dvdrecorder, or some other variant.

To remove your CDs/DVDs:

• In the GNOME desktop, right-click the CD icon and select Eject from the context menu. If you’re using the KDE desktop, select the Device Notifier icon in the Panel, then select the CD icon to eject.
• On the command line, type umount /media/cdrom, or change cdrom to whatever you had to use to mount the item.

How to Get Help on Linux

You may find yourself needing more help using Linux than you do using more pervasive operating systems, like Windows. Fortunately, Linux provides fairly easy ways to find help, as shown here:

Type This . . .	To Find This . . .
man -k [keyword]	Search a database for commands that involve the keyword. Can also be used as apropos [keyword].
info [command]	Display a file’s help information in an alternate format.
man [command]	Display a file’s help information.
whatis [command]	Display a short blurb about the command.