First of all, do not use $USERNAME in your BASH script. $USERNAME is a BASH variable that contains the current user's name. In fact, it is generally a bad idea to use UPPERCASE variables in BASH. Most BASH environment variables are upper case and that can lead to confusion. It is good practice to have your variables lower case.
Also, since I imagine you want to do this using an HTML form, you cannot have BASH read from STDIN. Modify tour script to take the user name as an argument:
BASH:
#!/bin/bash
user=$1;
DISPLAYNAME=`ldapsearch -p xxx -LLL -x -w test -h abc.com -D abc -b dc=abc,dc=com sAMAccountName=$user | grep displayName`
if [ -z "$DISPLAYNAME" ]; then
echo "No entry found for $user"
else
echo "Entry found for $user"
fi
Perl:
#!/usr/bin/perl
use CGI qw(:standard);
use CGI::Carp qw(warningsToBrowser fatalsToBrowser);
use strict;
use warnings;
## Create a new CGI object
my $cgi = new CGI;
## Collect the value of 'user_name' submitted by the webpage
my $name=$cgi->param('user_name');
## Run a system command, your display_name.sh,
## and save the result in $result
my $result=`./display_name.sh $name`;
## Print the HTML header
print header;
## Print the result
print "$result<BR>";
HTML:
<html>
<body>
<form ACTION="./cgi-bin/display_name.pl" METHOD="post">
<INPUT TYPE="submit" VALUE="Submit"></a>
<INPUT TYPE="text" NAME="user_name"></a>
</form>
</body>
</html>
This should do what you need. It assumes that both scripts are in the ./cgi-bin/ directory of your webpage and are called display_name.sh and display_name.pl. It also assumes that you have set their permissions correctly (they need to be executable by apache2's user, www-data). Finally, it assumes that you have set up apache2 to allow execution of scripts in ./cgi-bin.
Is there a specific reason you want to use BASH? You could just do everything directly from the Perl script:
#!/usr/bin/perl
use CGI qw(:standard);
use CGI::Carp qw(warningsToBrowser fatalsToBrowser);
use strict;
use warnings;
## Create a new CGI object
my $cgi = new CGI;
## Collect the value of 'name' submitted by the webpage
my $name=$cgi->param('user_name');
## Run the ldapsearch system command
## and save the result in $result
my $result=`ldapsearch -p xxx -LLL -x -w test -h abc.com -D abc -b dc=abc,dc=com sAMAccountName=$name | grep displayName`;
## Print the HTML header
print header;
## Print the result
$result ?
print "Entry found for $name<BR>" :
print "No entry found for $name<BR>";
