# Introduction

This page can be accessed from www.math.uh.edu/~torok, under Teaching, as Introduction to Computing Resources.

I prefer to use Emacs as a text editor, because it has special support for these (and many other) languages. But any text editor is fine, as long as it does not introduce extra characters in the file.

Here is some basic customization for Emacs.

Here are the main topics. You can find more details about them in the corresponding section of the course.
A few links to examples are included below.
• SYSTEM SECURITY
Question:
To nobody!!!!!
Let me repeat: To nobody!!!!!
Why:
• The system admistrator does not need your password to perform maintenance on your account; he can always do anything, without any information from you!
• It happened a few times lately that users gave out their password (i.e., fell for a phishing scam). The damage done by the intruder meant significant time spent by the system admistrator to clean things up.
YOU WILL NOT GET OFF THE HOOK EASILY!
• Even after that, we can still be blacklisted for a while.
E.g., all e-mails from our server can be rejected.
• Linux
• see more details on the Linux page
• for details about some of the commands below, see the Commands link on the Linux page
• the terminal (a.k.a. shell, console)
• the file system: ls, pwd, cd, mkdir, rm, cp, mv, more, less
• running jobs in the background: &, ^-Z, ^-C, jobs, fg, bg
• file permissions: chmod
• aliases: e.g., alias rm 'rm -i', asks for confirmation before removing a file
• manual pages: man, info
• if there is a major problem
• printing: the department printer is in Room 644, and is called rm644
(it is probably the default printer for most applications)
In a terminal, do:
• "lpq" to see the printer (and the queue),
• "lprm JOB-NUMBER" to remove one of your jobs from the queue.
• The Internet
• browsers:
• use the icon, or
• mozilla, firefox, etc.
• e-mail: thunderbird, alpine, webmail, etc.
• To configure your mail client to access the dept. mail, instructions are on Dave's web-page, here.
• One can also configure alpine to read and write messages from outside the dept.
• from outside
• remote access: ssh
• file transfer: scp
• "important" sites
• Text editor
• Emacs (multifunctional, worth getting used to)
• available for Linux/Mac/Windows
• customize
• mouse or keyboard commands
• shell, other extended commands
• auctex (for LaTeX)
• many others, e.g. kile for LaTeX
• HTML, CSS
• Examples:
• viewing the source code
• should be located in the directory ~/.www, ~/public or something similar
• the file that is opened by default is index.html (maybe Welcome.html works too)
• set access permissions: all execute the directory, all read the files
• CSS (Cascading Style Sheets): the good way to format your web-page
• LaTeX, BibTeX
• Math softwares
• Windows stuff
• ooffice
• Linux on Windows
• https://www.cygwin.com/
• This gives a lot of the linux applications/feel on a Windows machine.
In particular, when you ssh to the math dept, the ALT/DELETE/etc. keys work well.
• After you install the basic cygwin stuff (see instructions at the web-site; do not install everything, that takes up a lot of space), you will get a terminal that has problems with the DISPLAY setting (at least in my case), so cannot open other terminals from there.
Execute in that terminal startxwin (xinit could be the same or better), this will give you a window from were to start as many xterm & as you need.
• Install (see the web-site) what you need.