Making Your Web Page Interactive with CGI

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Making Your Web Page Interactive with CGI

• TLN Technology Committee
• February 16, 1999

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What is CGI?
A method used by www pages to communicate with
programs run on the web server. Glossary of
Internet Terms
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Finding Scripts

• Matts Script Archive
• worldwidemart.com/scripts
• CGI Resource Index
• www.cgi-resources.com
• Web Scripts
• awsd.com/scripts/

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Downloading

• Once youve found the script you want, download
  it and all the associated readme and html files.
• Be sure to download in ascii text mode.
• If available, save individual files instead of
  .zip file. This is the easiest way to ensure
  that the files are saved in ascii format.
• If you must use the .zip file, open files in word
  after unzipping them to save them in ascii format.

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Recognizing Ascii Format
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Customizing Scripts
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Customizing Scripts

• The first line of the .pl script must read
• !/usr/bin/perl
• NOT !/usr/local/bin/perl
• Change script name to name.cgi
• The .pl tag is not recognized on the server.
• Only scripts with the .cgi tag will run properly.

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Customizing Scripts

• The absolute path should be structured as
  follows
• /mnt/web/guide/worldwidemart/scripts/
• /home/lvcc/lvcc/www/cgi-bin/
• The url path to the designated file is the full
  path
• http//tln.lib.mi.us/lvcc/cgi-bin/scriptname.cgi
• http//tln.lib.mi.us/lvcc/relatedwebpage.htm

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Uploading Files
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Creating the CGI Directory and Uploading Files

• The CGI-BIN Directory
• Working in your FTP software
• Open your www directory
• Create a new folder at the host within the www
  directory.
• Name the folder cgi-bin
• Uploading Files
• Working in your FTP software
• Upload .cgi files to cgi-bin directory
• Upload .htm files to the regular www directory

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Setting Permissions

• CHMOD

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Changing Read/Write/Execute Access for CGI Files

• Permission settings for each associated file
  depends upon the action of the script.
• The readme file will usually tell you which
  permissions to assign to each file.

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Chmod in Linux/Unix

• Www Long List of Directory

drwxr-xr-x 2 lvcc users 1024 Jan 15
1002 cgi-bin -rw-r--r-- 1 lvcc users
1213 Jul 17 1996 momdad.htm -rw-r--r-- 1 lvcc
users 6520 Jul 2 1998
money.jpg -rw-rw-rw- 1 lvcc users
2968 Jan 7 1915 mypet.htm -rw-r--r-- 1 lvcc
users 1942 Jun 22 1998 mypetadd.htm

• Cgi-bin Long List of Directory

-rw-r--r-- 1 lvcc users 394 Aug 5
0954 folks02.gif -rwxr-xr-x 1 lvcc users
24292 May 11 1998 formmail.cgi -rwxr-xr-x
1 lvcc users 11340 Jun 22 1998
mypet.cgi -rwxr-xr-x 1 lvcc users
11380 Jan 14 1998 pineknob.cgi
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Changing Read/Write/Execute Access for CGI Files
chmod urwx,grx,orx form.cgi
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CHMOD by Numbers

• Readme files will often use numbers to designate
  chmod
• settings.
• First digit u
• Second digit g
• Third digit o
• 4 (r) 2 (w) 1 (x) 7
• 4 (r) 1 (x) 5

chmod urwx,grx,orx form.cgi and chmod 755
form.cgi result in the same action.
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Running The Script
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Testing and Troubleshooting

• Scripts must be uploaded and permissions changed
  before they can be tested.
• Usually, a minor adjustment will correct script
  error messages.
• Incorrect directory information or a misplaced
  slash will prevent a script from running.

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Common Error Messages
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The Form Mail Script In Action
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