When you need to make a call for system resources try to see (or search in portuguese) if similar command are available on builtin funtions...

$ perldoc -f readlink
readlink EXPR
readlink
        Returns the value of a symbolic link, if symbolic links are
        implemented.  If not, gives a fatal error.  If there is some
        system error, returns the undefined value and sets $! (errno).
        If EXPR is omitted, uses $_.
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This resource is new for me, but my first try is perldoc local or via web. (the second is CPAN! ;)