from Ohio State University.
How do I set my PATH?
The syntax for setting your path is slightly dependent on which shell you
are using. Most people end up with a C-shellish shell (like tcsh or csh)
instead of a Bourne-ish shell (like sh, bash, ksh). If you aren't sure what
shell you are running, look at the output of either
To read all the particulars for setting environment variables you should
look at the man page for your shell (i.e. man bash for bash, or man tcsh
For Bourne like shells (bash, sh, ksh...), the syntax is:
For C-shell like shells (csh, tcsh...), the syntax is:
set path = ($path ~cs421/bin ~/bin)
means to keep the existing PATH and then append it with the other
These commands can either be typed at the terminal each time you login,
or you can add it to your .bashrc for bash shell or .cshrc for csh or
tcsh so that each time you login, the PATH is already set. After
modifying your .cshrc or .bashrc, you will need to either source it
or log out and log in again for your changes to take effect.
Please also note that if you're running tcsh, creating your own
.tcshrc will toss out a lot of EWS-specific setup in
.cshrc, so don't do that.
How do I download files quickly with wget?
When we make assignments, we sometimes include supplementary files,
whether it be actual source code or test input or output. These files may
be downloaded using standard browser techniques (by selecting "Save as"
or equivalent) or by using the wget program.
The program wget is available on the EWS machines where you are expected
to do your development. The wget program is a part of the GNU project.
UIUC has a mirror of GNU's FTP site as part of UIArchive.
To retrieve a file by its URL, the syntax is simply
To retrieve an entire directory of files, use
wget -r --level=1 the-url-pointing-to-the-directory
More options are available to wget; see wget -h.
How do I run a script I downloaded?
In the past, we have sometimes had students download scripts as part of a
project build. To be able to run a script requires that what you have
downloaded have the executable mode bit set, which you would do with the
command chmod. As an example, let us say that you downloaded a script
called gen_output, and you needed to run it. You may need to execute this
chmod command before you are able to run gen_output:
chmod u+rx gen_output
Of course, if you do not have "." on your path, to execute this script,
you may need to run the script like this:
As always, you should refer to the man pages for the commands that you
use. The man pages for wget and chmod are available on the EWS systems.
How do I read the CS 421 newsgroup?
The CS course newsgroups can be found on the CS department
USENET server, news.cs.uiuc.edu. The group for this course is
class.cs421. To use this server, you must log on using your
netid and a special news server password.
For more information about newsgroups, including instructions
on how to set up your newsreader to access the groups,
as well as how to set your news server password, visit
How do I handin my MPs?
Read the individual MPs for the format of the handin and the files
required for each MP.
The handin program is now available on the EWS machines. You may
submit your assignments as many times as you like, but only the last
submission will be graded.
If you submit an assignment by its deadline, you may still submit the
assignment again during the 48hr Late Extension (provided the late
extension is offered). Of course, we will only grade your last submission
and the 20% late penalty will apply.
Please note that the handin program does not necessarily check to make
sure your assignment compiles. You must make sure your assignment
compiles with our grading script (available from the CS421 website),
or you will not receive credit for your assignment.
If you have problems with the handin program, please let one of the TAs
To use the handin program:
1. Login to dcllnx1.ews.uiuc.edu
Note: It should work with any dcllnx machine (dcllnx2, dcllnx3,
etc...) or any eelnx machine
2. To see information about mp1, including the status of your
~cs421/bin/handin -i mp1
3. To submit mp1, change into your work directory (this directory should
contain the file mp1.ml) and run
~cs421/bin/handin -s mp1
4. To force the handin program to accept a late submission of mp1, run
~cs421/bin/handin -f -s mp1
The above is a place holder, and probably not quite right.
5. For more details, run
On a specific MP, can we use functions we defined
in previous questions?
Unless we specify otherwise, the answer is yes.
Are we allowed to write helper functions?
As long as such helpers do not impede other requirements of the
question (such as requiring the solution, overall, to be tail
recursive), and as long as we don't specify otherwise; the answer