Remember to put <code></code> tags around your code. I simplified and cleaned up your code:

#!/usr/bin/perl

use strict;
use ExtUtils::MakeMaker qw(prompt);

my $curl_info = prompt(\&login);
if ($curl_info == 0) {
    print "Login successful\n";
}
else {
    die "Login not successful\n";
}    

sub login {
    system("curl -s -u user:password 
    -d 'ee45b45b5-b471-472d-96e4-481c65174ad0:4d808028-4c73-4489-b9b4-
+b05b296aa3b0'
    -X POST    
    http://localhost"); 
}
exit 0;
[download]

Update: To address the CLI question, I used this. At the cmdline, type

test.pl http://www.examplesite.com/sessions?
[download]

 
#!/usr/bin/perl

use strict;
use ExtUtils::MakeMaker qw(prompt);
use WWW::Curl::Simple;
print $WWW::Curl::Simple::VERSION;

my $url = shift @ARGV;
my $curl = WWW::Curl::Simple->new;

my $curl_info = prompt(\&login);
if ($curl_info == 0) {
    print "Login successful\n";
}
else {
    die "Login not successful\n";
}    

sub login {
    system("curl -s 
    -u user::password
    -d 'ee45b45b5-b471-472d-96e4-481c65174ad0:4d808028-4c73-4489-b9b4-
+b05b296aa3b0' 
    -X POST  
    --url $url");
}
exit 0;
[download]