Aludra Unix Basics

Disclaimer

Things change on our developer machines. If you notice anything wrong with these instructions, please let the TA know. Similarly, if you feel some topic is missing, let us know as well.

X-windows and FTP client

You can download the X-Windows software from the ISD software download site (note that the Windows 2000 version of X-Windows will work for Windows XP). Follow the installation instructions from the ISD site (they are checked). Also, download a FTP client of your choice.

To make sure you can connect to aludra.usc.edu using X-Windows, we will go over using the basic X-Windows commands below in Lab1, please pay attention to them because you will need to use them repeatedly throughout the class:

1. Open X-Windows by going to the Start menu, clicking on Programs, and then selecting the X-Win32 icon.

2. Open your Telnet window by going to the Start menu, clicking on Run, and then typing in telnet aludra.usc.edu.

3. When the telnet window appears, type in your login information.

4. Now that you are logged into Aludra UNIX server, in your Telnet window, you have to tell the UNIX server where to send your X-windows.

a. You must find the IP address of your own computer by going to run, type command, and then ipconfig /all in the prompt window.

b. In the Aludra Telnet window, type in setenv DISPLAY ip_address:0, where ip_address = the ip address you just found from ipconfig /all

c. Then type in xterm.

d. In a few seconds, a X-windows should pop up.

Getting around in UNIX

We will go through a short tutorial in class to make sure you can execute the basic commands in Unix (For our purposes, we will be using Emacs). However, if you're not familiar with Unix/Linux and proficient in at least one Unix-based editor, PLEASE make sure you read up and familiarize yourself with Emacs by going to the below links since you'll be using it extensively in CSCI201. YOU HAVE TO GET YOUR CODE RUNNING ON YOUR UNIX ACCOUNTS FOR PROPER GRADING.

http://www.xemacs.org

Emacs Basics

Starting up Emacs

1. Start up Emacs by typing in emacs in the Telnet window

a. The display in Emacs is divided into three regions. The top region is called the text window, which displays the document you plan on editing.

b. At the bottom of the text window, there is a single mode line. The mode line gives information about the document and the Emacs session.

c. The bottom line of the Emacs display is called the minibuffer, this holds the space for the commands that you give to Emacs by, and displays status information, the commands are discussed below.

2. Modern emacs has a Windows-like interface with menus that you can control with the mouse.

3. Experienced emacs users most often use keyboard commands.

a. Many commands in emacs are started by typing the Control key followed by a letter, e.g. c-s is incremental search.

b. Emacs also uses [Control-X] to initial a command, e.g. c-x c-f will initiate the find-file command.

c. You can also access commands by name using [Escape-X] or [Alt-x]. These appear in the command line as M-x and then you type the command (using spc for name completion), e.g., Alt-x shell will open a shell in emacs.

4. Most commands can be cancelled with Control-G.

5. To exit Emacs and return to the UNIX shell, type [Control-X-Control-C].

a. If you have made changes to the buffer since the last time you saved it to disk, Emacs will ask you if you want to save.

b. Type y for yes, or n for no.

6. Online Help: Emacs has an on-line help system that can be invoked by typing [Control-H].

a. If you type the question mark (?), Emacs will present a list of help topics you can choose.

Working with Buffers in Emacs

Buffers are work spaces. You can have many buffers in an emacs session. When you open a file, it is put in a buffer. When you save a file buffer the file is rewritten. Save often.

· You can move from buffer to buffer by using the Buffers menu.

· c-x b Moves you to another buffer. If you don't type a name, it defaults to the last buffer.

· c-x 2 Divides the window into 2 buffers. Very Useful.

· c-x 1 Puts the buffer into a single window.

Working with Directories in Emacs (Using the Dired Command)

Entering Dired

C-x d or M-x dired: To invoke Dired. To display the Dired buffer in another window rather than in the selected window, use C-x 4 d (dired-other-window) instead of C-x d.

Moving around in the Dired Buffer

SPC or n or C-n : To move to the next file in the listing
p or C-p :To move a previous file in the listing

Visiting Entries in Dired (VERY IMPORTANT)

f or e: Visit the entry described on the current line. If the entry is a file, it opens it. If the entry is a directory, a dired on that directory is opened. If the entry is the ".." then a dired is opened on the parent directory.
C-o Same as f or e, but opens the entry in a new buffer. Very useful.
v View the file described on the current line. File cannot be edited, i.e., view only.

Deleting Files with Dired

d Marks this file for deletion.
u Remove deletion flag on this line.
x Delete the files that are flagged for deletion.
# Marks all auto-save files (files whose names start and end with `#') for deletion
~ Marks all backup files (files whose names end with `~') for deletion
. (Period) Flag excess numeric backup files for deletion.
% d regexp RET Flag for deletion all files whose names match the regular expression regexp (dired-flag-files-regexp).

Operating on Files (notice the capitalized command letters)

C newname RET Copy the specified file (dired-do-copy).
R newname RET Rename the specified file (dired-do-rename).
H newname RET Make hard links to the specified files (dired-do-hardlink).
S newname RET Make symbolic links to the specified files (dired-do-symlink).
M modespec RET Change the mode (also called "permission bits") of the specified files (dired-do-chmod).
G newgroup RET Change the group of the specified files to newgroup (dired-do-chgrp).
O newowner RET Change the owner of the specified files to newowner (dired-do-chown).
P command RET Print the specified files (dired-do-print).
Z Compress or uncompress the specified files (dired-do-compress).
L Load the specified Emacs Lisp files (dired-do-load).
B Byte compile the specified Emacs Lisp files (dired-do-byte-compile).

Shell Commands in Dired (Only for experts)

The dired command ! (dired-do-shell-command) reads a shell command string in the minibuffer and runs the shell command on all the specified files. There are two ways of applying a shell command to multiple files:

o If you use `*' in the shell command, then it runs just once, with the list of file names substituted for the `*'. The order of file names is the order of appearance in the Dired buffer.

o If the command string doesn't contain `*', then it runs once for each file, with the file name added at the end.

o % u Rename each of the selected files to an upper case name (dired-upcase).

o % l Rename each of the selected files to a lower case name (dired-downcase).

o % R from RET to RET, % C from RET to RET, % H from RET to RET, % S from RET to RET These four commands rename, copy, make hard links and make soft links, in each case computing the new name by regular expression substitution from the name of the old file.

File Comparison with Dired using diff

= Compare the current file (the file at point) with another file that you are asked for.
M-= Compare the current file with its latest backup file (dired-backup-diff).

Subdirectories in Dired

A Dired buffer displays just one directory in the normal case; but you can optionally include its subdirectories as well.
The simplest way to include multiple directories in one Dired buffer is to specify the options `-lR' for running ls.
But usually all the subdirectories are too many; usually you will prefer to include specific subdirectories only. You can do this with the i command:

i Insert the contents of a subdirectory later in the buffer.

Moving Over Subdirectories

C-M-n Go to next subdirectory header line, regardless of level (dired-next-subdir).
C-M-p Go to previous subdirectory header line, regardless of level (dired-prev-subdir).
C-M-u Go up to the parent directory's header line (dired-tree-up).
C-M-d Go down in the directory tree, to the first subdirectory's header line (dired-tree-down).

Updating the Dired Buffer

g Update the entire contents of the Dired buffer (revert-buffer).
l Update the specified files (dired-do-redisplay).
k Delete the specified file lines---not the files, just the lines (dired-do-kill-lines).

Dired and find

· You can select a set of files for display in a Dired buffer more flexibly by using the find utility to choose the files.

To search for files with names matching a wildcard pattern use M-x find-name-dired.
If you want to test the contents of files, rather than their names, use M-x find-grep-dired.
The most general command in this series is M-x find-dired, which lets you specify any condition that find can test. It takes two minibuffer arguments, directory and find-args

Working with a File in Emacs

1. To read a disk file into an Emacs buffer, type the command [Control-X-Control-F], then type the name of the file, and then [Return], and Emacs will load the file into a buffer, and display it in the text window.

2. To save the contents of the buffer to a disk file, type [Control-X-Control-S].

3. To write the contents of the buffer to a different file with the command [Control-X-Control-W], then type the name of the file, and then [Return].

4. To create a new file, use [Control-X-Control-F], then type the name of the file, then [Return], and an empty document will appear in the text window.

5. To use file name completion, type part of the name of the file you want, and press the [Spacebar] or [Tab] key to complete a file name. If Emacs displays a few or more potential matches, continue typing in more of the file's name, and keep pressing file completion key until you get the file you want.

Working with the text window in Emacs

1. To insert text into a buffer, or the text window, move the cursor to where you want the text to appear and type.

2. To Delete text just press delete or use one of the following:

a. [Control-D] deletes forward one letter.

b. [Control-K] deletes from the point to the end of the line.

c. [Escape-D] deletes forward one word.

d. [Escape-Delete] deletes backward one word.

3. To select, move the cursor to where you want to begin the selection and type [Control-Spacebar], which sets the mark, and move the cursor to the other end of what you are trying to select. This will select the whole section.

4. To cut, type [Control-W].

5. To paste, type [Control-Y], but only pastes the most recently-cut text.

6. To paste in earlier cuts, type [Escape-Y], which cycles every time you type it, but you must first type [Control-Y] first for [Escape-Y] to work.

7. To copy, type [Escape-W].

8. To undo, type [Control-_] (Underscore).

Running a unix shell from within emacs

To open a Unix shell, you type: M-x shell
This creates a buffer, named *shell*, that allows you to run ant or any other unix command without leaving emacs.
The shell buffer can be searched, saved, etc. It is just another emacs buffer.
M-x rename-uniquely To rename the *shell* buffer. You can then create a new *shell* buffer using `M-x shell'.
alt-p Puts the last run command back in the buffer. VERY USEFUL.

Help Commands

C-h help-command: first character in lots of useful help commands
C-h t help-with-tutorial: command to run the tutorial
C-h i information: describes most of the emacs commands in man style pages
C-h k describe-key: tells you what a particular key stroke does
C-h a command-apropos: prompts for a string and then searches for all emacs commands that contains that string
ESC ? also does command-apropos
C-h ? help-for-help: describes how to use the help facilities

File Reading and Writing Commands

C-x C-f find-file: first prompts for a filename and then loads that file into a editor buffer of the same name
C-x C-s save-buffer: saves the buffer into the associated filename
C-x C-w write-named-file: prompts for a new filename and writes the buffer into it

Cursor/Screen Movement Commands

C-a move cursor to (at) beginning-of-line
C-e move cursor to end-of-line
C-f move cursor forward one character
C-b move cursor backward one character
C-n move cursor to next line
C-p move cursor to previous line
C-v scroll file forward by one screenful
ESC v scroll file backward by one screenful
ESC < go to beginning-of-buffer
ESC > go to end-of-buffer
ESC f move cursor forward one word
ESC b move cursor backward one word

Copy and Delete Commands

C-d delete-char: delete character under cursor
ESC d delete-word: delete from cursor to end of word immediately ahead of the cursor
C-k kill-line: delete the rest of the current line
C-@ set-mark-command: mark is used to indicate the beginning of an area of text to be yanked
C-w kill-region: delete the area of text between the mark and the current cursor position
C-y yank: insert at current cursor location whatever was most recently deleted
ESC w copy-region-as-kill: copy area between mark and cursor into kill-buffer so that it can be yanked into someplace else

Search and Replace Commands [The most often used commands]

C-s incremental search: prompts for text string and then searches from the current cursor position forwards in the buffer
C-r incremental search backward: searches from the current cursor position to end of buffer for text string
ESC % query-replace: prompts for a search string and a string with which to replace the search string
C-s C-s will do an incremental forward search using the last search string. VERY USEFUL.
C-r C-r will do an incremental backward search using the last search string. VERY USEFUL.

Window and Buffer Commands

C-x 0 zero-window: deletes current window
C-x 2 double-window: splits current window into two parts, allowing you to edit at two different locations in the same file or permitting you to view two different files at the same time
C-x b switch-to-buffer: display a different buffer on the screen
C-x o other-window: move the cursor to the other window (assuming that you have two windows/buffers open at once)
C-x C-b list-buffers: lists those buffers currently loaded into emacs

Exiting Emacs, Fixing Mistakes and Other Important Stuff

C-x C-c save-buffers-kill-emacs: when you are finished editing, to save the edited but unsaved buffers and to return you to the UNIX prompt
C-g keyboard-quit: if while typing a command you make a mistake and want to stop, this aborts a command in progress
C-u universal-argument: if you want to do a command several times, type this command followed by a number (for the number of times) followed by the command you wish repeated
C-x u undo: undoes the last command typed, in case you made a mistake
ESC x execute-extended-command: prompts for the name of an emacs command; allows you to execute a command if you know roughly what it is called but cannot remember the key strokes for it

Some common UNIX commands

Working with Directories:

ls: list files and directories
ls –a: list all files and directories
mkdir: make a directory
cd directory: change to named directory
cd: change to home-directory
cd ~: change to home-directory
cd ..: change to parent directory
pwd: display the path of the current directory

Copying a Directory: Very Useful

a. cp -i -r existingDirectory newDirectory
This does a recursive copy of all files and subdirectories.

b. For example, after you unzip v1, you'll have an agentsV1 directory (or something like that). Then, before modifying anything you need to copy it to a directory whose name might be agentsV3:
cp -i -r agentsV1 agentsV3

c. YOU SHOULD ALWAYS HAVE A RUNNING VERSION OF YOUR WORK. Every time you are going to modify something running, you should copy it as a backup.

Working with Files:

cp file1 file2: copy file1 and call it file2
mv file1 file2: move or rename file1 to file2
rm file: remove a file
rmdir directory: remove a directory
cat file: display a file
more file: display a file a page at a time
head file: display the first few lines of a file
tail file: display the last few lines of a file
grep 'keyword' file: search a file for keywords
wc file: count number of lines/words/characters in file

A Few More Complex UNIX commands:

*: match any number of characters
?: match one character
man command: read the online manual page for a command
apropos keyword: match commands with keyword in their man pages

Preparing your Bash Shell

Shells are an important concept in Unix. There are many different shells out there so it's important to find one you're comfortable with. We use the Bourne-Again Shell (BASH) so that's what most of these instructions will be geared towards.

- bash - to invoke the bash shell simply type bash. If you want Bash to be your default login shell type chsh in the command line and follow the instructions on changing your login shell. I only recommend this if you feel really comfortable messing around in Unix and with Bash.

- You will be creating a .bashrc file with commands that will be executed when you enter a bash shell.

Setting up Java, ANT, and JUnit

Ant is a Java-based build tool that makes managing and building your Java projects MUCH easier. For more details on Ant, make sure you check out the Ant User's Manual. The Ant setup script calls the setup script for the Java 1.5.0_06 JDK so all we have to do is call the Ant setup script in our .bashrc file. Junit is a regression testing framework for Java programs. It is used for unit testing Java programs; you will be doing a lot of unit testing in class.

Using your favorite Unix text editor (pico, vi, or emacs) type the following: emacs ~/.bashrc (replacing emacs w/ whichever text editor you want to use).
Enter in the following at the bottom of your .bashrc file (it's ok if your .bashrc file is empty):

#export JAVA_HOME=/usr/usc/jdk/1.5.0_06

export JAVA_HOME=/usr/usc/jdk/default
export PATH=/usr/usc/ant/default/bin:$PATH

export CLASSPATH=$CLASSPATH:/home/scf-22/csci201/junit3.8.1/junit.jar
ulimit -v 1840000

To see if you installed Java correctly, type java -version. You should see a message reading java version "1.5.0_06" or something similar.
To see if you set up Ant/Java correctly, type source ~/.bashrc and then type ant. You should see a message saying that build.xml does not exist. That means Ant and Java are installed and working correctly.
Junit is properly installed if the "ant test" target runs successfully. You'll do it in the lab.