Finally, after my last foray (in 2007) into developing RoR applications in Windows, I finally decided to do so in Linux.
Would you believe it, it took a retiree who loves to try out new operating systems to convince me to try out Ubuntu 9.04 ? He actually prefers Mandriva Spring 2009 :-)
So using my usual modus operandi, I googled for 'How to install ruby and ruby on rails on ubuntu 9.04" and got
http://mohamedaslam.com/install-ruby-on-rails-on-ubuntu-904-jaunty-jacklope/
Let's see what are the steps
Ruby installation
First we need to update the repositories.
Er... what's sudo and more importantly where do I type it ?
Did a further search and came across something called the Terminal and landed on
https://help.ubuntu.com/community/UsingTheTerminal
which says :-
"Under Linux there are GUIs (graphical user interfaces), where you can point and click and drag, and hopefully get work done without first reading lots of documentation. The traditional Unix environment is a CLI (command line interface), where you type commands to tell the computer what to do. That is faster and more powerful, but requires finding out what the commands are."
-- from man intro(1)
For some tasks, especially things like system configuration, it makes sense to use the terminal, and you'll probably have seen instructions on help pages or
forums similar to:
sudo gobbledegook blah_blah -w -t -f aWkward/ComBinationOf/mixedCase/underscores_strokes/and.dots
It is often assumed that you know how to use the terminal - and anyone can manage typing and backspacing. But there are some crafty shortcuts which can make your life a lot easier:
- How to move around in a terminal window and edit the text that you type there.
- Some Linux commands for basic tasks.
- Different ways to open a terminal, how to work with multiple terminals, etc.
Using this page
- This page will help familiarize you with basic GNU/Linux shell commands.
- It is not intended to be a complete guide to the command line, just an introduction to complement Ubuntu's graphical tools.
All command names will be in bold.
Commands needing to be typed will be in "bold with quotes".
- All of the commands on this page are to be issued from a command prompt in a terminal.
Note that the terminal is case sensitive. User, user, and USER are all different to Linux.
Starting a Terminal
In Gnome (Ubuntu)
The terminal can be found at Applications menu -> Accessories -> Terminal.
In Xfce (Xubuntu)
The terminal can be found at Applications menu -> System -> Terminal.
In KDE (Kubuntu)
The terminal can be found at KMenu -> System -> Terminal Program (Konsole).
Commands
sudo: Executing Commands with Elevated Privileges
Most of the following commands will need to be prefaced with the
sudo command if you will be working with directories or files not owned by your account. This is a special command which temporarily gives you access to change computer settings. The terminal will ask you for your password. Please see
RootSudo for information on using sudo.
File & Directory Commands
pwd: The pwd command will allow you to know in which directory you're located (pwd stands for "print working directory"). Example: "pwd" in the Desktop directory will show "~/Desktop". Note that the Gnome Terminal also displays this information in the title bar of its window.
ls: The ls command will show you the files in your current directory. Used with certain options, you can see sizes of files, when files were made, and permissions of files. Example: "ls ~" will show you the files that are in your home directory.
cd: The cd command will allow you to change directories. When you open a terminal you will be in your home directory. To move around the file system you will use cd. Examples:
To navigate into the root directory, use "cd /"
To navigate to your home directory, use "cd" or "cd ~"
To navigate up one directory level, use "cd .."
To navigate to the previous directory (or back), use "cd -"
To navigate through multiple levels of directory at once, specify the full directory path that you want to go to. For example, use, "cd /var/www" to go directly to the /www subdirectory of /var/. As another example, "cd ~/Desktop" will move you to the Desktop subdirectory inside your home directory.
cp: The cp command will make a copy of a file for you. Example: "cp file foo" will make a exact copy of "file" and name it "foo", but the file "file" will still be there. If you are copying a directory, you must use "cp -r directory foo" (copy recursively).
mv: The mv command will move a file to a different location or will rename a file. Examples are as follows: "mv file foo" will rename the file "file" to "foo". "mv foo ~/Desktop" will move the file "foo" to your Desktop directory but will not rename it. You must specify a new file name to rename a file.
- To save on typing, you can substitute '~' in place of the home directory.
Note that if you are using mv with sudo you can use the ~ shortcut, because the terminal expands the ~ to your home directory. However, when you open a root shell with sudo -i or sudo -s, ~ will refer to the root account's home directory, not your own.
rm: Use this command to remove or delete a file in your directory.
rmdir: The rmdir command will delete an empty directory. To delete a directory and all of its contents recursively, use rm -r instead.
mkdir: The mkdir command will allow you to create directories. Example: "mkdir music" will create a directory called "music".
man: The man command is used to show you the manual of other commands. Try "man man" to get the man page for man itself. See the "Man & Getting Help" section down the page for more information.
df: The df command displays filesystem disk space usage for all mounted partitions. "df -h" is probably the most useful - it uses megabytes (M) and gigabytes (G) instead of blocks to report. (-h means "human-readable")
du: The du command displays the disk usage for a directory. It can either display the space used for all subdirectories or the total for the directory you run it on. Example:
user@users-desktop:~$ du /media/floppy
1032 /media/floppy/files
1036 /media/floppy/
user@users-desktop:~$ du -sh /media/floppy
1.1M /media/floppy/
free: The free command displays the amount of free and used memory in the system. "free -m" will give the information using megabytes, which is probably most useful for current computers.
top: The top command displays information on your Linux system, running processes and system resources, including CPU, RAM & swap usage and total number of tasks being run. To exit top, press "q".
uname -a: The uname command with the -a option prints all system information, including machine name, kernel name & version, and a few other details. Most useful for checking which kernel you're using.
lsb_release -a: The lsb_release command with the -a option prints version information for the Linux release you're running, for example:
user@computer:~$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 6.06 LTS
Release: 6.06
Codename: dapper
Adding A New User
Options
The default behaviour for a command may usually be modified by adding a --option to the command. The ls command for example has an -s option so that "ls -s" will include file sizes in the listing. There is also a -h option to get those sizes in a "human readable" format.
Options can be grouped in clusters so "ls -sh" is exactly the same command as "ls -s -h". Most options have a long version, prefixed with two dashes instead of one, so even "ls --size --human-readable" is the same command.
"Man" and getting help
![/!\](https://help.ubuntu.com/htdocs/ubuntunew/img/alert.png "/!\")
man command,
info command and
command --help are the most important tools at the command line.
Nearly every command and application in Linux will have a man (manual) file, so finding them is as simple as typing "man "command"" to bring up a longer manual entry for the specified command. For example, "man mv" will bring up the mv (Move) manual.
Move up and down the man file with the arrow keys, and quit back to the command prompt with "q".
"man man" will bring up the manual entry for the man command, which is a good place to start!
"man intro" is especially useful - it displays the "Introduction to user commands" which is a well-written, fairly brief introduction to the Linux command line.
There are also info pages, which are generally more in-depth than man pages. Try "info info" for the introduction to info pages.
Some software developers prefer info to man (for instance, GNU developers), so if you find a very widely used command or app that doesn't have a man page, it's worth checking for an info page.
Virtually all commands understand the -h (or --help) option which will produce a short usage description of the command and it's options, then exit back to the command prompt. Try "man -h" or "man --help" to see this in action.
Caveat: It's possible (but rare) that a program doesn't understand the -h option to mean help. For this reason, check for a man or info page first, and try the long option --help before -h.
Searching for man files
If you aren't sure which command or application you need to use, you can try searching the man files.
man -k foo will search the man files for foo. Try "man -k nautilus" to see how this works.
man -f foo searches only the titles of your system's man files. Try "man -f gnome", for example.
Other Useful Things
Prettier Manual Pages
Users who have Konqueror installed will be pleased to find they can read and search man pages in a web browser context, prettified with their chosen desktop fonts and a little colour, by visiting man:/command in Konqueror's address bar. Some people might find this lightens the load if there's lots of documentation to read/search.
Pasting in commands
Often, you will be referred to instructions that require commands to be pasted into the terminal. You might be wondering why the text you've copied from a web page using ctrl+C won't paste in with ctrl+V. Surely you don't have to type in all those nasty commands and filenames? Relax. Middle Button Click on your mouse (both buttons simultaneously on a two-button mouse) or Right Click and select Paste from the menu.
Save on typing
Up Arrow or ctrl+p | Scrolls through the commands you've entered previously. |
Down Arrow or ctrl+n | Takes you back to a more recent command. |
Enter | When you have the command you want. |
tab | A very useful feature. It autocompletes any commands or filenames, if there's only one option, or else gives you a list of options. |
ctrl+r | Searches for commands you've already typed. When you have entered a very long, complex command and need to repeat it, using this key combination and then typing a portion of the command will search through your command history. When you find it, simply press Enter. |
History | The history command shows a very long list of commands that you have typed. Each command is displayed next to a number. You can type !x to execute a previously typed command from the list (replace the X with a number). If you history output is too long, then use history | less for a scrollable list. |
Change the text
The mouse won't work. Use the Left/Right arrow keys to move around the line.
When the cursor is where you want it in the line, typing inserts text - ie it doesn't overtype what's already there.
ctrl+a or Home | Moves the cursor to the start of a line. |
ctrl+e or End | Moves the cursor to the end of a line. |
ctrl+b | Moves to the beginning of the previous or current word. |
ctrl+k | Deletes from the current cursor position to the end of the line. |
ctrl+u | Deletes the whole of the current line. |
ctrl+w | Deletes the word before the cursor. |
More ways to run a terminal
You can also get it with a function key
You can run more than one - in tabs or separate windows
AptGetHowto - using apt-get to install packages from the command line.
grep Howto - grep is a powerful command line search tool.
CommandlineHowto - longer and more complete than this basic guide, but still unfinished.
HowToReadline - information on some more advanced customization for the command line.
For more detailed tutorials on the Linux command line, please see:
