Slide 5.7: Listing book information (cont.)

Listing Book Information (Cont.)

Once the button List or Help of the top part of the previous interface is clicked, the CGI Perl script below will be activated. It mainly performs the following two tasks:

Use the Unix utility sort to list all book information with the titles sorted.
Use the Unix utility grep to search for a book of the specified ISBN. The syntax of grep is
```
     grep  regular-expression  filename
```
It searches text file filename for a pattern regular-expression and prints all lines that contain that pattern. For security reason, check whether or not the ISBN is a 10 to 15 -alphanumeric characters before applying the system( ) function.

~wenchen/public_html/cgi-bin/351/week5/ListBooks.pl

#!/usr/bin/perl 
use CGI; 
$query = new CGI; 
$act   = $query->param( 'act' ); 
 
if ( $act eq "List" ) { 
  $select = $query->param( 'select' ); 
  if ( $select eq "all" ) {
    print ( "Content-type: text/plain\n\n\n\n\n" );
    system( "sort  books.txt" )
  }
  elsif ( $select eq "one" ) {
    $ISBN = $query->param( 'ISBN' ); 
    # Remove the white spaces before and after the ISBN.
    $ISBN =~ s/^\s*(.*?)\s*$/$1/g;
    $_ = $ISBN;
    if ( /\w{10}/ || /\w{11}/ || /\w{12}/ || /\w{13}/ || /\w{14}/ || /\w{15}/ ) {
      print ( "Content-type: text/plain\n\n\n\n\n" );
      system( "grep  $ISBN  books.txt" );
    }
    else {
      print( "Content-type: text/html\n\n" );
      print( "Wrong ISBN: $ISBN" );
    }
  }
  else {
    print( "Content-type: text/html\n\n" );
    print( "No such option: $select" );
  }
}
elsif ( $act eq "Help" ) {
  print ( "Content-type: text/html\n\n" );
  system( "/bin/cat Help.html" );
}
elsif ( $act eq "Home" ) {
  print ( "Content-type: text/html\n\n" );
  system( "/bin/cat FPDemo.html" );
}
else {
  print( "Content-type: text/html\n\n" );
  print( "No such option: $act" );
}