Cygwin Notes
Chris Riesbeck
Last updated: July 3, 2009
My C and C++ course uses the gcc compiler and the
Unix environment, both for consistency, and to expose you to the platform
used by many practitioners in computer science. Unix / Linux and gcc are available
on Linux,
on MacOS X machines after installing the XCode Developer tools, and
on Windows, after installing Cygwin. This
page is about setting up Cygwin for Windows.
Cygwin is a Linux-like environment for Windows. It can be downloaded for
free from http://www.cygwin.com. This
is the environment that will be used to demonstrate things in class.
If you have Cygwin, but with GCC version 3,
see these instructions for how to switch.
System requirements
You need Windows XP or Vista. Cygwin comes with an installer that lets you
get just the Unix tools
you need (there are 100's). For typical courses, you
only need the Gnu C++ compiler and some standard utilities, requiring about 200 megabytes
of disk space.
Installing Cygwin
Cygwin is fairly simple to install. You first download a small installer
program. Then you run this installer to download the Cygwin packages
you need. The installer takes care of downloading and installing not only
the files you ask for, but any files those files require.
The instructions below should get you going. If you'd like more
information,
see the Cygwin setup notes.
- Go to
http://www.cygwin.com.
- Click on the icon that says "Install Cygwin Now."
- A dialog box will appear asking where you want to save the installer
file setup.exe. Put it whereever
you normally keep installer files. I recommend renaming it
cygwin-setup.exe, so that you will recognize it if
you want to run it again in the future.
- After the installer file has downloaded, run it.
VISTA USERS: Run the setup program as Administrator. Right-click
on the setup program icon and select "Run as Administrator".
When the installer asks how you want to get the Cygwin files,
select the first option. This will download the files you pick
and then install them automatically.
Click Next >.
When the installer asks where you want to put the Cygwin files on your machine,
you can use the default c:\cygwin, or any other place
where you have a reasonable amount of space.
VISTA USERS: Check the Just Me option, not All Users.
Click Next >.
When the installer asks where you want to put Cygwin's temporary files,
you can use the default, which will be a directory in your user document
and settings directory. These files can be deleted later if you need
the space.
Click Next >.
When the installer asks what kind of connection you want, just
use the default first option.
Click Next >.
When the installer asks which site to download from, pick a location
near you. I chose Argonne National Laboratory.
Click Next >.
Now the installer shows you the various software packages
you can download. Because there are so many, they're organized
into groups, like directories in a file system. The
Archive group has the zip software packages, and the Devel
has many developer software packages.
To see things better, first enlarge the dialog box to full screen.
Click on the plus (+) sign to the left of Archive to open that group,
look for zip and unzip. If either one currently
says Skip, click it once to tell the installer to download it.
The installer will automatically
select any other required auxiliary packages -- some packages require dozens
of other packages.
Warning: Auxiliary packages are not automatically
unchecked if you click again to select a different version or to
go back to Skip. If you click on the wrong package I recommend
clicking the < Back button to return to the previous dialog, then
Next > to start over.
Click on the plus (+) sign to the left of Devel
to open that group, scroll down and select gcc4 and gdb,
if they currently say Skip. Do not select gcc -- that's the older
GCC version 3.
If you already have GCC version 3, get GCC version 4
and see these instructions for how to switch.
Scroll down further and select make.
Click Next >.
The Cygwin installer will now download the requested packages and
install them. When it's done, it will ask you if you want to create
a desktop icon for the Cygwin command shell, and an entry in the
Windows Start menu. I recommend that you at least take the
desktop icon.
To start the Cygwin shell, just double-click
the desktop icon. This will open a command window, similar to
Microsoft's DOS shell, but
instead of DOS commands, you have Unix, including the Gnu C++ compiler.
Creating a home directory
Unix, and therefore Cygwin, starts you off in your "home"
directory when you open the shell window. Cygwin by default will
create a home directory for you inside
the Cygwin directory, which can be a problem if you need to reinstall
Cygwin later. Therefore, it's better to define a home directory
in a safer place, such as your EECS 211 projects directory.
You do this by defining a Windows environment
variable called HOME.
Right-click on your My Computer icon and select Properties
from the menu. The System Properties dialog box will appear.
Click on the Advanced tab.
Click on Environment Variables.
Click New under User variables.
Type HOME into the Variable name field and
whatever directory you are using for EECS 211 code into the
Variable value field.
Click OK to
save your changes.
Now when you open a Cygwin window, it will put you in the directory
you specified in HOME.
Here's what to do if you already have GCC 3 installed on your computer:
- Use the Cygwin setup program to download and install gcc-4.
- Start a Cygwin shell.
- Enter the command
gcc --version. If it says GCC 4.x for some
x, you're done.
- Otherwise, enter the command:
/usr/sbin/alternatives --config gcc.
Note the double-dashes.
- Cygwin should list the versions of GCC available. Enter the number
to select gcc-4 and hit return.
- Now try
gcc --version. If it says GCC 4.x, you're done.
- If it still says GCC 3.x, it may be because you followed someone's advice (to
remain nameless here) and changed the gcc.exe shortcut to be gcc-3.exe.
- In Cygwin, or in Windows, go to the cygwin\bin folder
and find the file gcc.exe. If it's more than 1K in size, and there's
no file gcc-3.exe, rename gcc.exe back to gcc-3.exe.
- Try steps 4 through 6 again. If that fails, make an appointment to
see me.
Comments? 
Let me know!
