General Questions

This is an collection of Answers to Frequently Asked Questions for the UC Davis Math Dept.

• How can I use VNC on the math servers?
• How can I use putty ssh to connect to the math servers?
• How do I FTP files to and from my math account?
• How do I combine two PDF files into one?
• How do I connect to the campus network from home?
• How do I edit text files on my math account?
• How do I find contact information for someone on campus?
• How do I get an SSH client for Windows, MacOS, etc?
• How do I keep /etc/resolve.conf from being overwritten by DHCP?
• How do I make my dualbooting Linux/Windows system have the right time in both?
• How do I make sure other people cannot read files in my home directory?
• How do I obtain a central campus account?
• How do I obtain a math account?
• How do I read files off my floppy disk?
• How do I reduce or remove the DHCP timeout delay if my computer cannot find a DHCP server?
• How do I use SmartSite ( https://smartsite.ucdavis.edu ) under Linux?
• How do I verify the md5 checksum of a file?
• How do I write a good trouble report?
• So I'm teaching a class which meets outside of the math building, what should I do?
• What department servers can I log into with ssh?
• acroread compains about UTD-8 charset not supported, how do I fix?

There are two parts to using VNC. You have to initiate a VNC server on the math server you want to connect to. Once that server is started, you can connect to it with a VNC client program as many times as you want as long as that VNC server is still running.

1. Using an ssh program, connect to a math server (e.g. point.math.ucdavis.edu)
   
2. Use the command 'vncserver'
   
3. If this is the first time you are starting vncserver, you will be prompted for a password. This password will be needed when you connect with the VNC client program.
   
4. The vncserver program will give you a line similar to:
   New 'point.math.ucdavis.edu:3 (leng)' desktop is point.math.ucdavis.edu:3
   
5. Make a note of that line. You will need it for your VNC client. The above line tells you that your vnc server is on the host point.math.ucdavis.edu with a session number of 3.
   

Connecting with a VNC client:

1. Start your VNC client program.
   
2. Enter the hostname of the server followed by the session number. This may be in the form of 'point.math.ucdavis.edu:3' although this may vary depending on the VNC client you use.
   
3. When connected, you can run X11 programs from the server and they will show up on your computer in the VNC window.
4. Optional: You may want to start a gnome-session with the command 'gnome-session &' from the console window that first appears. This will give you the gnome desktop with menus, window widgets, etc. If this is troublesome try running 'gnome-wm &' instead

Download the putty SSH program (for windows) from http://www.chiark.greenend.org.uk/~sgtatham/putty/download.html and save it to your desktop.

The first time you use PuTTY, you will need to set it up to connect to the math servers.

Start the putty ssh program.

You will get the 'PuTTY Configuration' window.

1. Enter 'round.math.ucdavis.edu' for 'Host Name'.
2. Enter 'round' for 'Saved Sessions'.
3. Click 'Save'.

You have now created a profile for the math server 'round' in putty.

Now when you want to connect to the math server round.math.ucdavis.edu, you can do the following:

1. Open the putty ssh program that you saved to your desktop.
2. Select the profile for 'round' you created under 'Saved Sessions'.
3. Click 'Open'.
4. An ssh window will now appear connecting you to round. You will be prompted for your username and password. No letters or characters will appear as you type your password. This is for security purposes.
5. Once connected, you can start matlab, mathematica, etc.

[ls]

FTP is not supported for security reasons (login, pw, & data all being sent as plaintext). Instead we urge you to use Secure Copy (SCP), which is based on Secure Shell (SSH). You can use scp just like cp. For example to move a file from your math home dir to the current directory on your Linux computer at home you could type:

# scp myusername@round.math.ucdavis.edu:~/myfile.txt .

If you have MacOSX you can use scp from the terminal window just like Linux.

If you have MacOS8 or 9 you can use MacSSH or MacSFTP which can be found using google.

[mw]

One way is to convert them into postscript files, conbine them, and then turn back into a PDF. Example:

$ ls
frogs.pdf
tiger.pdf
$ pdf2ps frogs.pdf frogs.ps
$ pdf2ps tiger.pdf tiger.ps
$ cat frogs.ps tiger.ps >> frogs_and_tiger.ps
$ ps2ps frogs_and_tiger.ps frogs_and_tiger_fixed.ps
$ ps2pdf frogs_and_tiger_fixed.ps frogs_and_tiger.pdf

As requested Philip Sternberg submitted a more spiffy way (this should work on any system with gs installed):

gs -q -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -sOutputFile=merged.pdf source1.pdf source2.pdf source3.pdf etc.pdf

[zdj]

Use the UCD modem pool. Connection instructions can be found at: http://www-noc.ucdavis.edu/remote.php
For further help with connecting to the UCD modem pool, please contact IT Express at 754-HELP.

Central Campus Pools:
Faculty         754-7701
Student         754-7720
Staff           754-7711

Two popular text editors on linux are vi and emacs. They can be started with

# vi filename.txt

or 

# emacs filename.txt

There are many online tutorials available for the two editors. We suggest looking through a few and finding one that suits you

vi tutorials from google

emacs tutorials from google

Go to the UC Davis Directory or use the whois command.

example whois command:

[zjohnson@after zjohnson]$ whois Vanderhoef@whois.ucdavis.edu
[truman.ucdavis.edu]
Name                     UCD MailID                       UCD LoginID
Larry Vanderhoef         (lnvanderhoef)                   lnvander
Rosalie Vanderhoef       (rsvanderhoef)                   rsvander
You have new mail in /var/spool/mail/zjohnson
[zjohnson@after zjohnson]$ whois lnvanderhoef@whois.ucdavis.edu
[truman.ucdavis.edu]
Name:               Larry Vanderhoef
Email Address:      lnvanderhoef@ucdavis.edu
Delivery Host:      mulan.ucdavis.edu
UCD LoginID:        lnvander
UC NetID:           47808
Title:              Chancellor
Department:         Chancellor's Office
Mailstop:           0550 Mrak Hall
Telephone:          (530)752-2065
[zjohnson@after zjohnson]$ 

[zdj]

Usually by going to a search engine say google.com and typing in "free ssh" and your operating system ie: "free ssh windows", or "free ssh macos" will get you some links to help you find a free ssh client.

For windows I like to use putty along with PSCP or WinSCP.

For Mac OS I like Nifty Telnet SSH

For Mac OSX, you can use the built in OpenSSH program. Just open the Terminal program found in Applications/Utilities and use ssh from the command line.

For Linux I like OpenSSH, which is included with most Linux dists.

For other operating systems please check http://www.freessh.org/

Also if you are unsure of which servers you should log into:

Undergraduates: round.math.ucdavis.edu, point.math.ucdavis.edu, line.math.ucdavis.edu, plane.math.ucdavis.edu
Everyone else: fuzzy.math.ucdavis,edu, logic.math.ucdavis.edu

[zdj]

Make a file named /etc/dhclient-enter-hooks
It should be executable, and contain:
                                                                                
# tell function that re-writes resolv.conf to do nothing
make_resolv_conf() {}

[zdj]

In /etc/sysconfig/clock change line that reads "UTC=true" to "UTC=false".

[zdj]

If you want to restrict access to all of your existing files except files located in public_html, and make it so files created by you in the future will not be readable by anyone but you please run the following commands: (you can cut and paste them directly into another terminal window to run them).

echo "umask 077" >> ~/.bash_profile
chmod 700 ~/.bash_profile
source ~/.bash_profile
chmod -R 700 ~
chmod -R 755 ~/public_html
chmod 755 ~ 

If you are new to the university and have not gotten a central campus login (sometimes called a kerberos account) here is how you get one.

With photo ID in hand go to IT-Express walk-in which is located in 182 Shields Library. A map showing where Shields Library is can be found here: http://www.cevs.ucdavis.edu/map/map_detail.cfm?assetInfo=112

[zdj]

If you are enrolled in a class which requires use of the math lab go to:

http://www.math.ucdavis.edu/comp/class-accts

If you are a..

undergrad math major faculty graduate student instructor

Please see any of the staff to request an account (bring proof of identity). [zdj]

Windows floppies:

Use mtools, type the command man mtools for complete usage information.

examples:

mdir a:                     (list contents of floppy)
mcopy a: .                  (copy all files on floppy to current directory)
mcopy a:filename.txt        (copy filename.txt on floppy to current dir)

OSX floppies:

need info...

[Admins]

To reduce this timeout under Red Hat Linux:

first make a file named /etc/pump.conf containing:

retries 1
timeout 5

Then copy /sbin/ifup to /sbin/ifup.orig

Edit /sbin/ifup and replace the following 2 lines:

if [ -x /sbin/pump ] && /sbin/pump ${PUMPARGS} -i ${DEVICE} ; then

and

elif [ -x /sbin/dhcpcd ] && /sbin/dhcpcd ${DHCPCDARGS} ${DEVICE} ; then

with

if [ -x /sbin/pump ] && /sbin/pump ${PUMPARGS} -c /etc/pump.conf -i ${DEVICE}+; then

and

elif [ -x /sbin/dhcpcd ] && /sbin/dhcpcd ${DHCPCDARGS} -t 12 ${DEVICE} ; then

On the diskless terminals or desktop systems with Ubuntu installed you can connect to a webdav server by navigating through the menus Places -> Connect to Server... Once there fill out the information needed for a connection. Here is my information as an example (be sure to change zjohnson to your own SmartSite id):

Service Type                =  Secure WebDAV (HTTPS)
Port                        =  8443
Folder                      =  /dav/users/zjohnson
Name to use for connection  =  SmartSite

Under Linux simply run

# md5sum file

If you are running windows check out http://www.iay.pwp.blueyonder.co.uk/threel/tech/tools/md5.htm

[zdj]

Write email to help@math.ucdavis.edu

Be as detailed as possible. If you answer the following questions it should be an excellent report:

What room and building are you sitting in?
What is the name or IP address of the computer you are using?
Did you get an error, if yes, can you cut and paste it into the report?
On which system did you attempt to perform the function which failed?
What time did the problem occur?

[mw]

1. Find the building where it is located with the map found here: http://www.cevs.ucdavis.edu/map/
2. Check the registrar website for information about the room here: http://registrar.ucdavis.edu/schedule/html/sum_display.cfm?sort=1
3. Register your laptop's MAC address so it can be used with the ethernet network connections in the class rooms here: https://computingaccounts.ucdavis.edu/cgi-bin/services/index.cgi
4. If it happens to be in a computer lab this site may be useful: http://lm.ucdavis.edu/

[zdj]

The following department login servers are for general use. You can also reach them using the alias round.math.ucdavis.edu

• point.math.ucdavis.edu
• line.math.ucdavis.edu
• plane.math.ucdavis.edu
• sine.math.ucdavis.edu
• cosine.math.ucdavis.edu
• tangent.math.ucdavis.edu

• fuzzy.math.ucdavis.edu
• logic.math.ucdavis.edu

[ls]

Add the following line at the starting of the "acroread" file.

LANG=C; export LANG