# close
close STDOUT;

# redirect
open STDOUT, '>', "/some/path/to/file" or die "Can't redirect STDOUT: 
+$!";
[download]

(see open)

Whether to close or redirect depends on how the child program is using them. Simply closing might not always work.

I'm not using them at least explicitly in the child program.

...but cvs might be. They're 'inherited' across the fork/exec.