Chapter 2 Getting Started

2. Chapter 2 Getting Started

3. What You Need to Get Started • Getting the appropriate FTP or Telnet software • Connecting to the Web server • Setting up your directories. • Getting the location of the Perl interpreter.

4. Connecting with Telnet • Connect to the Internet • Start Telnet. • On a Windows PC start Microsoft Telnet for Windows by clicking Start, Run, telnet. • Connect to your Web server with Telnet. • Log into the server.

5. An Initial Telnet Sreen

6. Successful Telnet Login

7. Connecting with FTP • Connect to the Internet. • Start FTP. • Connect to your Web server with FTP.

8. An Initial FTP Login Screen

9. A Successful FTP Login Screen

10. Navigating UNIX Directories

11. Navigating UNIX Directories - 2

12. Some UNIX Navigation Commands

13. Some UNIX Navigation Commands Unix Commands

14. Navigating UNIX Directories with FTP C:\Temp on PC Home dir on web server

15. Finding The Location Of Perl • Perl interpreter • A program that translates Perl program commands into commands that are understandable to a computer. • Runs your Perl programs and generates any output. • Its command name is simply perl. • It can be installed in any of several places on a Web server.

16. Finding Location Of Perl • Find the location of Perl Interpreter • Telnet onto Web Server enter: • which perl • where is perl Perl Interpreter Location

17. Starting Your Program Development Process • Each time you develop and run a program: • Create a program file and copy (or save) it into the correct directory. • Change your program’s access permissions. • Check your program’s syntax. • Run your program.

18. Create Your Program File • Editors are computer applications that enable you to create, change, and save files • Microsoft Windows,Notepadis a simple editor that works well for Perl development. • On UNIX systems, the Pico, Vi,and Emacseditorsare popular choices. • Will describe the use of Pico on a UNIX Web Server.

19. Starting Pico • Telnet into Web Server and enter “pico”

20. Starting Your First Program • Start Editor and enter the following: 1. #!/usr/bin/perl 2. # This program prints out a simple message 3. print “Steady Plodding Brings Prosperity\n”;

21. Program Entered in Pico

22. Run The Program • Save the program file on the web server. • Enter the full path to the program file to run. • For example • /home/perlpgm/perl-pgm-www/cgi-bin/simple1.cgi Home Directory Directories On Web Server Program File

23. Change the Program’s Permissions On A Unix Web Server • UNIX access permissions are used to define the access rights of your files • read permissions define if the file can be read • write permissions define if the file can be changed, • execute permissions define if the file can be executed as a program • You set access permissions for your user ID, your user ID’s group, and everyone else

24. Use The chmod command

25. Use The chmod command

26. Change the Program’s Permissions On A Unix Web Server • chmod 777 simple1.cgi - end-user and his/her work group and anyone else to read, write, or execute the file simple1.cgi. • chmod 755 simple1.cgi- end-user can read, write, or execute the filesimple1.cgi,but everyone else can only read or execute it. • chmod 644 simple1.cgi - you can read or write the filesimple1.cgi, but everyone else can only read it. (Good for data files).

27. Setting Permissions with FTP on a UNIX Web Server 1. Log into the Web server using the FTP command. 2. Navigate to the appropriate directories on the Web server. 3. Select the file you want to change on your Web server, then right -click it. A drop-down menu will appear. Select FTP commands, and then chmod. (See Next Slide). 4. Select the desired read, write, and execute access permissions for your user ID, your group, and anyone else.

28. An FTP Change Permission Screen

29. Check and Correct Your Program’s Syntax • syntax checking - verifies that program statements are grammatically correct as specified by the program language grammar • Check the syntax ofyour programs before attempting to run them.

30. To Check Your Program Syntax(on a UNIX Web Server) • establish a Telnet session, • navigate to the directory that contains the file, • enter perl –c filename,where filename is the program file whose syntax you want to. For example, • cd perl-pgm-www/cgi-bin • perl –c simple1.cgi • If no syntax errors then receive: • simple1.cgi syntax OK

31. Program with Syntax errors Missing quote mark

32. Running Your Program • At least two different ways to run your Perl programs: • Directly on a Web server or PC without a browser • Using your browser over the Internet.

33. Running Your Program - On A PC 1. Open a MS-DOS prompt window. • Click Start, Run and then enter command. 2. Run the program. • At the MS-DOS prompt, enter the location of Perl, followed by the location of your program: • C:\Perl\bin\Perl C:\temp\simple1.pl • Perl C:\temp\simple1.pl • You Can also use cd • cd C:\temp • Perl simple1.pl

34. Getting Ready to Run Your Program Over the Internet 1. To use a browser over the Internet, add the following MIME content-typeline: print “Content-type: text/html\n\n”;. 1.#!/usr/bin/perl 2.print “Content-type: text/html\n\n”; 3.# This program prints out a simple message 4.print “Steady Plodding Brings Prosperity\n”;

35. Change Program Process 1. Edit the program 2. Change the program. 3. Save the file. 4. Check the program’s syntax. 5. Run the program.

36. Running Your Program Over the Internet 1. Connect to the Internet. 2. Start your browser. 3. Enter the URL or Web address to your file 4. Check the program’s syntax. 5. Run the program. For example, assume saved the in a file called simple2.cgi in my cgi-bin directory on the Web server. Can execute by the following: http://perl-pgm.com/cgi-bin/simple2.cgi

37. Output Of Program Executed Over the Internet

38. Dealing with Problems • Many Web servers redirect the errors from CGI programs into a separate error log located on the server. • You may receive a generic, cryptic message when running program’s with errors. • Two common messages are Internal Server Error(Figure 2.17) and 500 Server Error.

39. Some Things to Check • Verify the program syntax. • Verify the access permission. • Verify the file has the proper extension. • Verify the program is stored in the correct directory. • Verify the correct Web address to your program. • Verify the first line has the correct of the Perl interpreter. • Confirm the accuracy of your MIME Content-type line.

40. An Internet Server Error

41. Generating HTML Statement from Perl Programs 1. #!/usr/bin/perl 2. print "Content-type: text/html\n\n"; 3. print "<HTML> <HEAD> <TITLE> Example </TITLE></HEAD>"; 4. print "<BODY>"; 5. print "<B><Font Size=5>This is a Test </FONT></B>"; 6. print "A very Interesting test"; 7. print "</BODY></HTML>";

42. Program Output

43. Summary • There are several different configurations you can use to develop CGI/Perl programs. • Using FTP and Telent are common • Steps to create a program: create with editor, enter program, set permissions, check syntax, and run the program. • Two statements are required: • First line identifies Perl interpreter location. • Second line specifies the MIME Content-type.