#!/usr/bin/perl

use strict;
use warnings;

my $name = shift;

my $func = "update_$name";

main->$func(); # "main" should be the namespace the functions are in.

sub update_test { print "!test\n" }
sub update_hello { print "hello!\n" }
[download]

The downside is that the first parameter to the function is its namespace. In the above example, it's "main". Note the output:

$ perl x.pl test
!test
$ perl x.pl hello
hello!
$ perl x.pl heheh
Can't locate object method "update_heheh" via package "main" at x.pl l
+ine 10.
[download]

The (more) normal way to do this is:

#!/usr/bin/perl

use strict;
use warnings;

my $name = shift;

my %updates = (
               test => \&update_test,
               hello => \&update_hello,
              );
$updates{$name}->();

sub update_test { print "!test\n" }
sub update_hello { print "hello!\n" }
[download]

Either way, you should check if the function exists before trying to run it, e.g., main->can($func) or exists $updates{$name}.