my $cmd = sprintf("perl %s", $update_location);
system($cmd);
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You could avoid shelling out /bin/sh and a new instance of perl via require:

require $update_location;
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This way your required script will also run with taint checking, which is always a good thing to do for CGI scripts (++ for the OP for that alone). Some points to be aware of:

• $update_location must be an absolute path
• it inherits globals from the current process
• it must return a true value; this can be done by placing a line containing 1; at the end of the script $update_location
• the invoking script MUST NOT be persistent (e.g. running under mod_perl or fastcgi) since requiring is done only once

This might fit - or not - your requirements; it is just another way to do it (and a safer one IMHO).