use warnings;
use File::Copy;

# The files 't1.txt', 't2.txt', 't3.txt',
# 't4.txt', and 't5.txt' all exist in the cwd.

for(1..5) {
   if (copy("t${_}.txt", "u${_}.txt")) {
      print "copied t${_}.txt to u${_}.txt\n";
   }
   else {print "$_: Copy failed\n"}
}

__END__
Outputs:

copied t1.txt to u1.txt
copied t2.txt to u2.txt
copied t3.txt to u3.txt
copied t4.txt to u4.txt
copied t5.txt to u5.txt