In Linux operating systems there is more incentive to learn and use the command line than in Windows, especially as Microsoft has relegated almost all functions to the GUI. For some tasks it may be more efficient to use the command-line interface (CLI), and for Linux purists and experts, that is often the preferred method. In any case, it is to your advantage to familiarize yourself with the CLI.
This page gives you a basic overview of the commands. For a tutorial you can also go to http://linuxcommand.org/.
A shell is a command-line interpreter: it takes commands and executes them. To do that, it implements a programming language. As you can probably guess, the CLI can be a powerful tool. You can write your own programs, called shell scripts, that can do a variety of things. However, we will focus on basic commands in this guide.
Bash (Bourne-again shell) is the default shell for most current Linux distributions (and Mac OS X) and can be run on most Unix-like operating systems. We make the assumption that you are running Bash, though some commands will work in other shells. To check what shell you are currently using, open the console, type
echo $SHELL, and press Enter. It should return a pathname ending with
In a shell <tab> is your friend. When using the CLI pressing tab once or twice produces very desirable results. One press will complete your command if there is only one possible filename matching what you're typing; pressing twice produces a list of possible filenames.
Most commands can be modified with arguments, which are specified after the command, that change the behavior of the basic command. Arguments can be fundamental to the command (e.g., a file is the argument to a delete command) or optional. In the latter case, arguments are preceded by a dash (
-) in Linux or a forward slash (
/) in DOS/Windows.
To see what arguments are available for a certain command, you can search the internet or, conveniently, read the man pages (short for “manual pages”) for that command. Man pages are self-contained documents that can help you more fully utilize the potential of the command line. Simply type
man before the command name (the argument), and press Enter. Press
q to leave a man page and return to the terminal.
Some commands require administrative access. If you are not already logged in as the root user, you must run these commands with the root user's privileges. You can do this either by typing
sudo at the beginning of the command or, alternatively, by running the
su command before executing any such command. In the case of sudo, you will be asked for your (user) password.
su, on the other hand, requires the use of the root password. (Note: The characters you type do not appear on screen. This is normal.)
Using the command
sudo bash or
sudo su, you can use bash as root, which can be useful when performing a series of administrative tasks. However, once you have finished, you should revert to your user account, using the command
exit (or the shortcut Ctrl-D).
Sometimes when asking for help with a problem, other users might ask you to give them the output of some commands (lspci, lsusb, ifconfig, and dmesg are a few faves in this category). To avoid long outputs that go past the screen, you can use the pipe symbol (”|”, the key right above Enter, or <Shift> + <Backslash>) to redirect the output of the command into a different program. Take this example:
sudo lsusb -vvv -s 1:02 sudo lsusb -vvv -s 1:02 | less
In the commands above, the first line will spit out everything the machine can tell you about one USB device, which will eat up several pages! By sending it to the 'less' text viewer, it displays it in sort of a reader, that lets you use up/down/pageup/pagedown to browse freely (press 'Q' to exit). But what if someone on the forums asked for the output? That's easy too… you can send it all directly into a file like this:
sudo lsusb -vvv -s 1:02 >> lsusb_output.txt
That command will dump the output into a file in your current folder, named 'lsusb_output.txt'. If there was already a file by that name, the » symbol will just add it to the end of the file.
For more information on a command, you can check the manual page. These are built into the system for each command that's installed (even the simple ones!). To open one, type:
man command_name_here man lsusb
That's it! The manpage will open up and show all kinds of information about the command. (Probably more than you ever wanted to know.) A sample manpage (for lsusb) can be seen here.
|Bash command||DOS command||Function|
|cat||type||Display file contents|
| cd || cd/chdir || Change directory to
|pwd||cd (by itself)||Displays the current directory|
|chmod||attrib||Set file permissions|
|date||date, time||Set/display date and time|
|diff||fc||Compare two files|
|df||Display free disk space|
|echo||echo||Display message on screen|
|free||mem||Display memory usage|
|fsck||chkdsk, scandisk||File system check|
|grep||find||Search for file(s) with given string|
|some_command | grep||Search the output of the command for string|
|history||??||Displays a list of your most recent commands|
|less||more||view a long text file or use with ||
|ls||dir||Display directory contents|
|ls -l||Like ls, but in a more readable format|
| find -name || dir /s || Search for file called
|mv||move, ren/rename||Move or rename files or directories|
|rm||del, deltree||Remove file(s)|
|uname||ver||Show system information|
|nano||edit||Launches a basic text editor|
|kwrite||Launches a GUI text editor|
|XandrosFileManager||Launches the Xandros file manager|
|ip addr||ipconfig /all||Reports your IP address|
|sudo ifconfig | grep "inet addr"||Reports your IP address|