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Redirection

CGI/Perl ProgrammingBy Diane Zak

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Objectives

• In this chapter, you will:

• Include the Location header in a script

• Include the Refresh header in a script

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Introduction• Documents often move on the Web

from one location to another– Link to new URL so user must click to go

to new location– Automatically forward the browser to a

new address• Immediately• After a period of time (seconds)

– META tag – HTML– Location Header – script– Refresh Header - script

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Redirecting a browser• Location header:

– Immediately redirects the browser– Syntax:

• print “Location: url\n\n”;

– Example:print “Location: http://www.rsp.com/public_html/chap12/error.html\n\n”;

• The 1st newline character identifies the end of the Location header

• The 2nd newline character inserts a blank line below the header to signal end of header section

• Location header used instead of Content-type header

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Redirecting a Browser

• Refresh header:– Waits a specified number of seconds before

redirection– Syntax:

• print “Refresh: seconds; URL=url\n”;

– Example:print “Refresh: 3; URL=“http://www.rsp.com/public_html/chap12/error.html\n”;print “Content-type: text/html\n\n”;

• Contains one newline character because it is used with the Content-type header

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Using a Refresh Header

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Using a Refresh Header

• Uses Refresh header to redirect the page in 3 seconds

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Using a Location Header

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Using a Location Header

If no Name was typed into the cara1.html page

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Summary

• You can use the Location header or the Refresh header in a CGI script to redirect the user’s browser to another location.

• The Location header redirects the browser immediately.– Syntax: print “Location: url\n\n”;

• The Refresh header waits for a specified number of seconds until redirection.– Syntax: print “Refresh: seconds; URL=url\n”;– Is used together with the Content-type header