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Maths Computer System FAQ

Here are some common questions and answers about the use of the maths computer system. If you can't find an answer here or if you find something is broken of if you have any suggestions please send e-mail to ops@maths.tcd.ie.

Disclaimer: Apologies for old information in this page. We hope to update it soon. (14/11/2011).

Questions

Answers

What are the rules?

We have a simple policy for use of the maths computer system.

How do I change my password?

You can change your password only when you are logged on to salmon. Then you can give the command passwd which will ask for your old password, and then the new one.

If the new password is too easy to guess then the password program will complain and make you choose a different password.

When you have finished your password will be changed on salmon. The rest of the machines will use your old password until midnight, when they will be updated.

I've forgotten my password - help!

If you have forgotten your password, please email ops@maths.tcd.ie (from another email address!) to make an appointment or ask in the School office (room 0.6). We don'yt send passwords by email. Please bring your ID card so we can check who you are!

How do I change my shell?

The shell given to newcomers on the maths Unix system is tcsh, which is fine for most people. We do not allow people to change their shells themselves, but if you mail ops@maths.tcd.ie we will be happy to change it for you. (We also have sh, csh, bash, zsh, though the dot files for these are not as well tested).

How do I forward my mail?

If you would like to forward your mail to a different address (for example newaddress@work.com) you should make a file called .maildelivery, which contains the line:
* * | A "/usr/local/bin/resend -r$(sender) newaddress@work.com"
Your mail should then be forwarded to this address.

Note - on many systems you can make a file called .forward, containing the e-mail address you would like mail forwarded to. Unfortunately this does not work on the maths system (as we use MMDF, not sendmail). More info about your maildelivery file can be found in manual pages: man maildelivery

How do I set up a vacation program?

Sometimes if you're on holiday, or away from computers for a while, you'd like to have an automatic reply sent to people, explaining that you're in the Bahamas and won't be able to read your email for a week. You can set this up by creating a file called .maildelivery, which contains the line:
* * | ? /local/mmdf/bin/rcvtrip $(sender)
You then create a file called tripnote with a message explaining why you are away: 

Hi, I'm at a conference until Monday 9 August. I will read
your email when I return. If you need to contact me
urgently call my mobile phone. - John Smith
More info about your maildelivery file and rcvtrip can be found in manual pages: man maildelivery and man rcvtrip

How do I get rid of junk mail?

Spamassassin is available to filter junk mail. To get Spamassassin to filter your mail, you need to make a .maildelivery file with the following lines at the top: 

* - | A         "/usr/local/bin/spamassassin-true-if-spam"
* - > +11!      junkmail
This will put all the mail which Spamassassin thinks is junk into a file called junkmail.

Occasionally, Spamassassin may mistake real e-mail for junk e-mail. You may want to check the contents of the junk mail folder from time to time. This can be done with the command mutt -f ~/junkmail or pine -f ~/junkmail, depending on which mail program you like to use.

If you trust Spamassassin not to make any mistakes, then could reject or destroy mail instead of putting it in a junk-mail folder.

Help, Spamassassin is junking mail from a friend!

Spamassassin does occasionally make mistakes. You can tell it that all mail from a particular address is good by editing .spamassassin/user_prefs and adding addresses to the whitelist_from list.

How do I get rid of virus mail?

Unfortunately clamav has not been working on our system for a while, but with luck it will be enabled again soon (11/2011).

Viruses via e-mail will most often only affect people who use Microsoft Windows, and so users of Unix systems tend to be able to ignore them. However, you may want to filter out viruses in your e-mail, either because you read your maths mail on a Windows PC or because you find receiving this sort of junk mail annoying.

If you want to filter virus mail, Clam AnitVirus is available. To get Clamav to filter your mail, you need to make a .maildelivery file with the following lines at the top: 


* - | A         "/usr/local/bin/clamscan-true-if-virus"
* - > +11!      virusmail
This will put all the mail which Clamav thinks is a virus into a file called virusmail.

You can use Spamassassin and Clamav at the same time by putting both the Clamav lines and the Spamassassin lines in your .maildelivery. You could even file the rejected mail from both into the same mailbox, by changing virusmail into junkmail in the lines above, for example.

If you would prefer to discard viruses, rather than filing them in a separate folder, you could replace the Clamav lines in your .maildelivery with: 


* - | A         "/usr/local/bin/clamscan-true-if-virus"
* - destroy +11!

How do get rid of mail from a certain person?

If you way want all mail from a certain person deleted before it gets to you. You can also do this with your .maildelivery file. Say you want to delete all mail from junk@mail.net then make a .maildelivery file containing the line:
From junk@mail.net destroy A -
Be careful - this will also zap mail from not-junk@mail.net!

You can replace the destroy with reject in which case the person will receive a piece of mail saying that their mail was rejected. For examples see /local/mmdf/premaildelivery or look at the man page for maildelivery.

How can I connect to my account from home?

There are a number of ways for connecting to your account from outside college... the preferred method is using ssh, an encrypted communications protocol.

A number of programs are available for this... firstly, the Java applet we have set up at http://www.maths.tcd.ie/ssh/ (convenient if you're traveling too!). There are also a number of programs you can download to your own computer... for Windows, the best one we have come across is PuTTY. Also available, but a larger download, is TTSSH.
For UNIX, you can install OpenSSH, which will require OpenSSL to be installed also.

My account is broken - what can I do?

Often when people are experimenting with their "dot" files they accidently break their account. This may mean that no commands can be found, or that they cannot log on from x-terminals. We have a program which will copy the files we give to newcomers back into your account.

To use this program say fix-my-account (or if things are really messed up /usr/local/bin/fix-my-account). Now answer the questions it asks you - it will not change anything without asking you.

My browser can't get stuff from outside college.

There are two reasons for this. If the problem is intermittent or short-term (less that a day) then it is probably a network problem and you will have to wait for it to go away.

If you never seem to be able to get at the outside world your browser (firefox, iceweasel, opera, konqueror -- there are lots installed) preferences are probably wrong. You need to find the proxy settings (either in your browser or in your desktop settings). For instance in firefox/iceweasel that is under Edit -> Preferences. Select Advanced tab, then Network, then Connection settings.

The simplest is to set it to "Auto detect proxy settings" and that should work now (in most browsers).

If that fails, the next best is to set "Automatic proxy configuration url" to http://wpad.maths.tcd.ie.

In the worst case (say with browsers in a phone, maybe, or skype perhaps) you may need to manually set proxies to proxy.maths.tcd.ie port 80.

(This section updated 11/2011.)

Netscape complains about a lock file when I start it.

This may mean that you have a netscape already running, but it is more likely that it got left behind by accident. You can remove it by typing:
rm ~/.netscape/lock

How do I print from Netscape?

See the section on printing below.

How do I find e-mail addresses in college?

If the person has a maths account you could try finger -l name, where name is the first name or surname of the person you are looking for. This may produce a lot of output, but will probably list the person you want.

If you are looking for a college e-mail address or phone numbers you can say consult the people finder page on the College local web page http://peoplefinder.tcd.ie/pls/peoplefinder

Staff in the School are listed on our web page http://www.maths.tcd.ie/people/ and there is always your favourite search engine.

How can I set up a home page?

The basic thing is that the files that constitute your personal web site must be in a directory ~/www (that is a subdirectory www of your hime directory, and there are issues with read and execute permissions.

So you must create the directory (or folder) ~/www and both it and all directories above it must be world executable. That would be your home directory essentially. Files in your ~/www that you want people to be able to access via the web must be world readable and the start page should be called index.php (although older style start pages of index.html or Welcome.html will get used in the absence of index.php).

There are various College policies and recommendations on web pages.

(Section added 20/11/2011.)

How can I display mathematical formulae in my web pages?

Perhaps the most convenient way (for relatively occasional formulae in a document) is to use MathJax, which is installed on our web server. If you include
<script src="/MathJax/MathJax.js" type="text/javascript">
MathJax.Hub.Config({
config: ["MMLorHTML.js"],
extensions: ["tex2jax.js"],
jax: ["input/TeX"],
tex2jax: {inlineMath: [["$","$"],["\\(","\\)"]]}
});
</script>
in the header section of your html document, it will work to put things like $\int \sin \theta \, d\theta$ in hour html code (and the display should be $\int \sin \theta \, d\theta$).

There are also programs that take a whole LaTeX source file and convert it to html (like tex4ht, tth or latex2html (but perhaps you wll find it easier to use pdflatex to make a pdf file, install that on your site with a link to it in a suitable place).

(Section added 20/11/2011.)

What software is available?

A rough list of software is available, but it is not comprehensive.

Can I read my maths mail from elsewhere?

Yes - you should be able to pick up your mail using pop3.maths.tcd.ie as your pop server and your maths username and password. Alternatively (and probably better) use imap.maths.tcd.ie as your imap server (and maths username + password).

It is now (Feb 2013) possible to send your mail through maths while not logged in to a mathe compuer, using your maths username and password. You should set your smtp server to smtp.maths.tcd.ie and to use port 587. This should work happily with Thunderbird or Microsoft Outlook, for instance.

We have a web interface at webmail.maths.tcd.ie. We hope to upgrade that to a newer version (fairly) soon! (02/2013).

I can't send mail when I'm logged on from my ISP!

If you are sending mail from home you will have to have set an SMTP server. For sending machines outside Maths, see above instructions, or you may be able to send using the smtp server of your ISP.

EMail from my from friend/colleague has suddenly stopped reaching me. What's wrong?

The Maths Department mail server does not accept mail from computers with invalid or incomplete DNS entries. A DNS entry is a mapping from a name such as "salmon.maths.tcd.ie" to an IP address - 134.226.81.11 in this case. In other words if I do "nslookup salmon.maths.tcd.ie" I should get 134.226.81.11. This is a forward lookup. If I do "nslookup 134.226.81.11" I should get back salmon.maths.tcd.ie. This is known as the reverse lookup.

Almost all computers have the forward lookup configured correctly. Unfortunately some do not have the reverse lookup correctly configured.

We have never accepted mail from hosts with incomplete DNS records - this policy greatly reduces the volume of spam we receive. However, until recently some email from hosts with bad DNS records was relayed to us from the main Trinity College mailserver - which did accept such mail. Now though, they too have tightened their policy and are refusing such mail. This means that the backdoor has closed, and you may have stopped receiving email from certain addresses.

The correct solution is for the DNS of your friend/colleague's mailserver to be corrected. They may need to contact their System Administrator or their ISP. Feel free to forward this explanation onwards.

The Check DNS web page will perform a quick test of the DNS for your computer.

Can I use the college get/put folders or my college disk space from maths?

Yes - you can access it using getputdir for get/put folders or freddir for individual disk space. This provides and interface like ftp. You can say cd, dir, get and put. Typing in help gives a list of commands. Say quit to finish.

You can set your college username with issname. (Need some student to check if this is still working! (11/2011) Email ops please.)

Can I use my maths disk space from college?

You should be able to use ftp on the college Macs and PCs to get and put files from the maths computers. "fetch" is a good ftp program for the Mac.

I've lost a file somewhere.

You can quickly check for a file you know the name of by saying locate filename, which will list all files of name filename on all the machines. This list is built every Friday, so the file must have been there last Friday to be listed.

How do I transfer a file to floppy?

Sorry, need to set something up for usb sticks, but it is not there yet (11/2011)

What sort of computer is hamilton?

We have a list of hardware being used in each machine.

Mathematica produces sick postscript!

If you want to produce useful ps output from graphics in Mathematica, (eg. that may be visualized with ghostview), you have to first change the graphics preferences from "Custom operator for low-resolution images" to "Built-in PostScript operator". These preferences are in the preferences submenu of the edit menu.

Thanks to Christoph Adam for this.

How do I print things?

How you print a file depends on what you want to print. The printers understand Postscript and plain text, but if you want to print anything else you will need to convert it into one of these.

You will also need to know the name of the printer you are printing to. They are named laser14, laser15, etc according to the room in which they are in. In the following examples I will use laser?? as the name of the printer.

Plain Text
Plain text can be printed using the command lpr -Plaser?? filename. You can produce a nicer output using the a2ps command - for example: a2ps -Plaser?? filename.
Postscript
Postscript files have names that usually end in .ps. You can print them using the command lpr -Plaser?? filename.ps. However you can not use a2ps on them! There are some nifty things you can do with psnup and psselect and friends.
LaTeX and TeX
To print a .tex file you first must make a .dvi file using the command latex file.tex or tex file.tex. Once you have your .dvi file you can print it using the command dvips -Plaser?? file.dvi.
In Netscape

To print in netscape choose "Print" in the "File" menu. A box will pop up. Find where it says "Print To:" and click the diamond to the left of "Printer". Then put the command lpr -Plaser?? in the print command box. Finally hit the "Print" button at the bottom of the box.

Note, If you are looking at a page in netscape which uses frames, then you should click on the frame you want to print in advance.

In Mathematica
Choose "Print" from the "File" menu. Click on the square to the left of "Print to" and put the command lpr -Plaser?? in the box to the right of "Print to". Hit the OK button.
PDF files from Acroread
Choose "Print" from the "File" menu. Click on the diamond to the left of "Printer" and put in the command lpr -Plaser??. Click "OK".
Microsoft Word/Excel/... Documents
Complain to the person who sent you the document and ask for it in a reasonable format.
Other File Formats
You can view many file formats in netscape and print them from there. If you want to convert a graphic to postscript for printing the program convert can be quite useful. You can say convert file.gif file.ps and then print file.ps. Remember to delete file.ps afterwards!
Duplex printing

Some printers now have duplex units installed, which allow printing to both sides of a sheet of paper. Selecting whether or not to print in duplex is accomplished via selecting the correct printer queue.

In public computer rooms, the default queues (eg laser??) are set up for duplex. If you need to print in simplex, you should add an "s" to the end of the printer name (for example lpr -Plaser??s)

Printers for staff are more commonly left as simplex by default. Therefore, to print in duplex from these, you should select (for example) lpr -Pwr06d.

Finally, for all printers with duplex units, in order to print landscape-orientated pages (for example, those produced by a2ps) properly in duplex, you should add an "l" onto the name of the printer (for example, lpr -Plaser??l).

I'm on Hogs! What can I do?

You can see the disk hogs list for your disk by typing hogs . If you are on this list it probably means that you need to delete old files and mail 'cos you are using more than your fair share of disk space. We have hints on how to clean up.

Help, my hello.cgi script won't work!

On some systems you can make a CGI script work by placing it in your www directory and calling it something like myscript.cgi. On our system we use the /www/common-cgi directory for users CGI programs. You can just copy your program into that directory, and then the URL for the script will be http://www.maths.tcd.ie/common-cgi/myscript.cgi.

Help, my hello.php script won't work!

To use PHP scripts in maths, you'll need to create a file called ~/www/.htaccess. This file should contain the lines:

Action php-script /common-cgi/php4
AddHandler php-script .php


Again, if you have any suggestions for improvements please let us know.

ops@maths.tcd.ie