Example 19-8. who.cgi

  #!/usr/bin/perl -wT
  # who.cgi - run who(1) on a user and format the results nicely
  
  $ENV{IFS}='';
  $ENV{PATH}='/bin:/usr/bin';
  
  use CGI qw(:standard);
  
  # print search form
  print header( ), start_html("Query Users"), h1("Search");
  print start_form( ), p("Which user?", textfield("WHO")); submit( ), end_form( );
  
  # print results of the query if we have someone to look for
  $name = param("WHO");
  if ($name) {
      print h1("Results");
      $html = '';
      
      # call who and build up text of response
      foreach (`who`) {
          next unless /^$name\s/o;            # only lines matching $name
          s/&/&/g;                        # escape HTML
          s/</&lt;/g;
          s/>/&gt;/g;
          $html .= $_;
      }
      # nice message if we didn't find anyone by that name
      $html = $html || "$name is not logged in";
      
      print pre($html);
  }
  
  print end_html( );