Robustness aside (as it suffers from the same lack of error checking the other proffered version below with system has :), it doesn't express the intent behind the code correctly. Backticks are for capturing the output from an external program; system is for starting an external program who's output you don't care about.

It's like using map in void context to iterate over a list in place of for; yes it "works", but if the line of code is not building a new list of values from an existing list then you're using the wrong "phrasing" (by which I mean 'not the clearest') to express your intent (map is for expressing transformation, for is for expressing iteration).

(And I won't go into the "PERL scripts" I've seen that basically consisted of a shebang line and then every line was shell commands in backticks . . . *shudder* :)

Update: Tweaked for perldoc link somewhere more relevant per prodding from kyle.