Complete by October 8, 1998. This is an ungraded assignment, but you need to complete it in order to do subsequent assignments.

Sooner or later you'll need to use Unix to run advanced programs. The favorite editor to use in conjunction with Unix is Emacs, so you should get familiar with Emacs basics too.

If you already know how to use Unix and Emacs then you don't need to do this assignment. Be sure you do know all the information covered here, however.

Getting Started | Learn Unix | Learn Emacs

Getting Started

There several ways to access Unix machines in the SIMS environment. (We will be using Solaris Unix, because that is the Unix that runs on the Sun machines that we use in the lab. FYI, Linux is an increasingly popular form of Unix and we might have this in the lab in future. The differences between these are supposed to be unnoticable, so you don't really need to worry about this.)

For the work in this course the following method of accessing Unix should work fine. On an NT machine, access the SecureCRT program at

Start\Programs\Internet\SSH-Telnet\SSH-info.sims
(You shouldn't use irony.sims for this assignment, as it is used for other purposes. This is the secure version of telnet we're supposed to use now. It encrypts your password over the network for you.)

You'll get some dialog boxes the first time you run this. Go ahead and make it your default telnet application in the first dialog box, and select Accept & Save in the second box. After this first time you won't have to repeat all these commands.

Once you're past all the dialog boxes, you'll get a prompt TERM = (xterm). Just hit Return when you see this. Now you're logged into a unix machine (called info.sims).

This is a very nice version of telnet. You'll notice the command menu at the top allows you to do cut and paste, change the keyboard mapping, and many other things.

Learn Unix

Read the information on Basic UNIX File Manipulation at http://socrates.berkeley.edu/Help/Unix/basicunix.html

Now do the following operations (after each task I show the appropriate unix command in italics).

• Create a new directory called stuff
• mkdir stuff
• Make stuff your current directory
• cd stuff
• Print the current directory
• pwd
• Create a new file called greeting containing the word "hello"
• echo "hello" > greeting
• Look at the contents of the file called greeting
• more greeting
• Copy this file to another file called greeting2
• cp greeting greeting2
• Remove the first file
• rm greeting
• Move up out of this directory to your home directory
• cd ..
• Check that you're really in your home directory
• pwd
• Go to the top of the groups directory
• cd /groups
• See what files and directories reside there
• ls
• Look at these files in more detail
• ls -l
• Go back to your home directory
• cd
• Check that you're really there
• pwd
Now read the information on UNIX Man Pages at http://socrates.berkeley.edu/Help/Unix/manpage.html
• Try out the man command at the Unix prompt.
• See what that more command was we used earlier.
• man more
• (The stuff under Synopsis indicates the different arguments that you can give to different variants of the command.)
• Find out how to make ls show you files whose names begin with a . (a period).
• man ls
• Try out the web version of the man pages at the Socrates Manpage Viewer (from the Man Pages help webpage).

Then read the Unix tutorial at http://riceinfo.rice.edu/Computer/Documents/Unix/UNIX1/unix1.html

This goes into more detail than the earlier tutorial and will repeat some of what you've just learned, but should make everything make fit together better.

Be sure to learn the parts about:

• Redirecting input and output.
• Wildcard characters. This is very useful to know about. Use some wildcard characters in conjunction with the ls command.
• Background jobs. This is quite useful to know about too, although you might not understand all the details from this explanation.

If you'd like more references, there is a list of recommended Unix guides at http://wss-www.berkeley.edu/unix/faq/books.html

Learn Emacs

Now learn some basics about the emacs editor. Emacs has a huge range of functionality but you only need to know the basics to get started. (Its name stands for Easy Macros.)

Emacs makes extensive use of the Control key, which can take getting used to. Something written as C-x C-c means first hold down the control key and press x (while still holding down the control key) and then do the same thing with control and c. (You can keep the control key held down for both the x and the c.)

You can run emacs from the Unix prompt by simply typing Emacs. This puts you in a buffer called *scratch*, which is temporary scratch space.

You save a buffer's contents into a file by typing C-x C-s.
You can get out of emacs by typing C-x C-c.
Undo the previous command with C-x u
(This means hold down control and x at the same time, then release the control key and hit the u.)

The Meta key (usage is written M-x, for example) is either the Alt key or the ESC key; you'll have to test it out on your system.

First read an emacs tutorial, for example http://yoda.cis.temple.edu:8080/UGAIWWW/help/emacs-tutorial.html

Now use tutorial materials prepared by Armando Fox. Go back to the unix prompt and do the following commands.

• Go to your home directory.
• Make a directory called emacs-tutorial
• Copy the files from the directory /groups/is202/emacs-tutorial into your emacs-tutorial directory.
• Move into your emacs-tutorial directory.
• Check that it is really your directory (use pwd).
• Now read the contents of the file called README (use the more command) and follow the instructions there for how to run the emacs tutorial.

Especially Useful Emacs Commands

Below I list what I consider to be especially useful emacs commands, omitting emacs macros, which get their own section, below.
• Search in the buffer. After you type the command, start typing in the letters of the string you are searching for. After you find the first hit on the string, you can type the command again and get the next and subsequent hits. When you get to the end of the file, the search begins again from the top of the file.
• C-s
• Replace string. I use this every day. It lets you replace one string of characters with another in the current buffer. After you type the command you enter a dialog with the system and it asks you what pattern you want to replace with what other pattern.
• M-x replace-string
• Query replace. I also use this every day. It's like replace-string except it pauses before each replacement and asks you if you want to replace that particular instance of the string. This is useful because sometimes it's hard to specify exactly the pattern you want to replace. If you want to replace the string you hit Return, otherwise you hit "n" (for no).
• M-x query-replace
• Help: This gets you into the comprehensive online help facility. Here is a nice webified description of the help options.
• C-h ?

Emacs Macros

There are some aspects of Emacs that make it especially useful and worthwhile learning. Probably the most powerful is the ability to write macros on-the-fly to do repetitive editing work for you.
The main idea is that you can ``capture'' a sequence of emacs commands and have the system repeat this sequence over and over again for you. Here's how it works.
• Tell the system you are starting to create macro.
• Type C-x (
• Now the system is recording the commands you type next. So type in the sequence of commands you want the system to record to be reused later.
• Once you're done with the commands
• Type C-x )
• Now you've defined a keyboard macro. To tell the system to re-execute the sequence of commands,
• Type C-x e
• You can tell the system to re-execute the command any number of times. Say you want to re-execute it 10 times.
• Type ESC 10 C-x e
• You can save macros to be reused later by assigning them a name with
• M-x name-last-kbd-macro

Emacs Initialization File

You probably want to create a customized startup file for emacs. You save this information in a file called .emacs in your home directory. You can store macros in this file and tell the system what mode to start up in by default. Here are some lines from my startup file along with notes as to why they are there

• This gets rid of that annoying startup message:
  (setq inhibit-startup-message t)
  
• This means set Auto Fill mode to be true. In Auto Fill mode, inserting a space at a column beyond `current-fill-column' automatically breaks the line at a previous space. So it does a nice wrap-around for you without your having to hit return at the end of the line.
  (setq auto-fill-mode t)
  
• By default emacs stores a backup copy of every file you edit with a ~ appended to the filename. I don't like this and so I turn it off.
  (setq make-backup-files nil)
  
• These next few are more advanced.
  
• You can also assign commands to keyboard sequences. (Be careful -- --you might override a command that does something else.) For example, I wanted a fast way to tell the system to go to a particular line number in the file, so I define the following:
  (global-set-key "\C-x\C-g" 'goto-line)
  Now when I type C-x C-g the system asks me what line number to go to and then goes there.
  
• You can tell emacs what mode to go into depending on the file extension of the file you are editing. If I am editing a Java file (whose name ends with .java) I want the system to use java-mode, if I'm editing a latex file I want it to use latex mode. To tell this to the system, I put the following in my .emacs file (the formatting is messed up in html):
  (setq auto-mode-alist
  '(("\\.c$" . c-mode) ("\\.lisp$" . lisp-mode)
  ("\\.java$" . java-mode)
  ("\\.cl$" . lisp-mode) ("\\.html$" . c-mode)
  ("\\.tcl$" . tcl-mode) ("\\.tex$" . latex-mode)))
  

Here is one emacs reference guide.
Here is another quick reference guide to emacs commands.

Here is a full version of the GNU Emacs Manual

Last modified Sept. 30, 1998. MAH