Why we choose UNIX

1
Why we choose UNIX

• Powerful
• Multi-user operating system
• Good programming tools
• Most heavy-duty database management systems
  started out on Unix
• Flexible  
• Thousands of tools that can be combined and
  recombined.
• Reliable
• Unix is hard to crash.

2
How to Access a UNIX Machine
telnet / ftp
telnet allows you to connect to other computers
and use softwares there ftp
allows you to retrieve files from other
computers.
3
Telnet

• TELetype NETwork
• A network protocol used on the Internet / LAN
• By extension, refers to the program which
  provides the client part of the protocol
• Once connected
• Log on as a regular user with access to
• application / software
• data
• A Telnet command request looks like this
• telnet rain.cise.ufl.edu

4
FTP

• File Transfer Protocol
• A network protocol used on the Internet / LAN
• Allow to transfer files to and from remote
  computers
• A ftp command request looks like this
• ftp rain.cise.ufl.edu

5
SSH

• Why SSH

• Download SSH
• http//www.openssh.org/

Figures from http//www.suso.org/docs/shell/ssh.sd
f
6
More about SSH

• Recommendation for Windows
• Putty as telnet tool
• http//www.chiark.greenend.org.uk/sgtatham/putty/
  download.html
• WinSCP as ftp tool
• http//winscp.net/eng/download.php
• Other choices
• ftp, telnet using command line in windows
• Other softwares
• Core FTP
• http//www.coreftp.com/download.html

7
Unix Commands

• man manual (man gcc)
• ls list directory contents (ls)
• pwd prints working directory (pwd)
• cd change directory (cd ltsubdirectorygt)
• mkdir create directory (mkdir ltnew directorygt
• rm remove a file (rm ltfile to removegt)
• Use r if removing a directory

8
Unix Commands(cont)

• cpcopy a file (cp ltsourcegtltdestinationgt)
• Use r if copying a directory
• mvmove or rename files (mv ltsourcegt
  ltdestinationgt)
• jpico text editor (jpico ltfile to editgt)
• gcc compiler (gcc sourceFile.c)
• -o option
• Directory shortcuts
• home directory
• .. parent directory
• . sub directory

9
Your First Program
Preprocessor interact with input/output of your
computer

• include ltstdio.hgt
• int main()
• printf("Hello World\n")
• return 0

You will see this at the beginning of nearly all
programs Tells computer to load file named
ltstdio.hgt ltstdio.hgt allows standard input/output
operations
10
Your First Program
Preprocessor interact with input/output of your
computer

• include ltstdio.hgt
• int main()
• printf("Hello World\n")
• return 0

Start point of the program
C programs contain one or more functions, exactly
one of which must be main int means that the
function main will "return" an integer value
11
Your First Program
Preprocessor interact with input/output of your
computer

• include ltstdio.hgt
• int main()
• printf("Hello World\n")
• return 0

Start point of the program
Start and finish of function
12
Your First Program
Preprocessor interact with input/output of your
computer

• include ltstdio.hgt
• int main()
• printf("Hello World\n")
• return 0

Start point of the program
Start and finish of function
Printing a line of Text
13
Your First Program
Preprocessor interact with input/output of your
computer

• include ltstdio.hgt
• int main()
• printf("Hello World\n")
• return 0

Start point of the program
Start and finish of function
Printing a line of Text
14
Your First Program
Preprocessor interact with input/output of your
computer

• include ltstdio.hgt
• int main()
• printf("Hello World\n")
• return 0

Start point of the program
Start and finish of function
Printing a line of Text
Finish and return value 0
A way to exit a function It means that the
program terminated normally in this case
15
Comments for programs

• Why need comments
• Good habit
• Readable to others
• Remind yourself
• How to comment
• / /
• //
• Effects on compiler
• Examples

16
Compiler

• What is compiler
• A computer program (or set of programs) that
  translates text written in a computer language (
  the source code) into another computer language
  (most time the executable file)
• Why we need a compiler
• Available C compiler in UNIX system gcc
• gcc sourcefile.c o exefile.exe

17
Text Editors

• Edit your code Using wordpad, or some text editor
  on your personal computer
• Need to transfer your program to UNIX machine
  using ftp
• Edit your code in UNIX using
• vi
• pico (jpico)
• emacs

18
Procedure
This is your C program. Type the code in any
standard text editor, and save it as
helloworld.c. Transfer it to rain.cise.ufl.edu if
necessary
Type gcc helloworld.c o helloworld.exe to
compile helloworld.c into helloworld.exe using
the gcc compiler
The gcc compiler generates corresponding
executable code named helloworld.exe. The
computer can execute this machine readable code
if you type ./helloworld.exe