Lab - Web

1. web page
   • How to set up and maintain Web pages
   • put home page in: $HOME/public_html/index.html
   • visible at: http://student.computing.dcu.ie/~username/
   • More on student.computing.dcu.ie

2. student.computing.dcu.ie
   • Linux cluster
   • It has access to your home directories (shared file system).
     e.g. your web dir:

      /users/mse1/USERNAME/public_html 
      /users/gdf1/USERNAME/public_html 
     

   • You do not have access to some of its directories (non-shared file system).
     e.g. its web dir, which is something like:

       /htdocs  
       /srv/www/htdocs  
       /local/apache/htdocs  
       etc.
     

     You have to be logged into the actual web server machine to see this.

   
   

   URL	maps to this file	on this filesystem
   http://student.computing.dcu.ie/	/local1/apache2/htdocs/index.html	non-shared
   http://student.computing.dcu.ie/STRING/	/local1/apache2/htdocs/STRING/index.html	non-shared
   http://student.computing.dcu.ie/~STRING/	/users/group/STRING/public_html/index.html	shared

   
   

3. More on the tilde convention:
   • Can use it at command-line:
     cd ~/bin is same as cd $HOME/bin
   • www.computing (also here) is running Solaris. Uses similar tilde convention for user web pages.

   
   

4. two web servers, two file systems:

   URL	server IP	server OS	links to files on
   http://student.computing.dcu.ie/~STUDENT/	136.206.11.245	Linux	Linux file system
   http://www.computing.dcu.ie/~STUDENT/	136.206.11.240	Solaris	Linux file system (same files as above). Solaris server can access Linux file system. Solaris command-line can access Linux file system. (*)
   http://www.computing.dcu.ie/~STAFF/	136.206.11.240	Solaris	Solaris file system (i.e. It knows based on userid whether to look on Solaris file system or Linux file system.)
   http://student.computing.dcu.ie/~STAFF/	136.206.11.245	Linux	Fails. Linux server cannot access Solaris file system. Linux command-line cannot access Solaris file system.

   (*) Solaris command-line can access Linux file system:
   When I am logged into Solaris machines, I can access Linux dirs:

    /users/mse1 
    /users/gdf1 
   

   Like the HTTP server, I am now "other" not "group".
   So I can't do an ls, but I can access file if I know its name:
   cat USER/public_html/index.html

   
   

5. make web page
   • make it link to sub-page, which links back to main page
   • "hide" it, and see it is now invisible
   • "norm" it and see it is visible

6. PHP
   • You can use PHP.
   • get your own PHP test page working

7. .htaccess
   • Re-direct errors to PHP script.