What's wrong with using backticks in a void context?

    `cp file file.bak`;

And now they think ``Hey, I'll just always use backticks to run programs.'' Bad idea: backticks are for capturing a program's output; the system() function is for running programs.

Consider this line:

    `cat /etc/termcap`;

You haven't assigned the output anywhere, so it just wastes memory (for a little while). Plus you forgot to check $? to see whether the program even ran correctly. Even if you wrote

    print `cat /etc/termcap`;

In most cases, this could and probably should be written as

    system("cat /etc/termcap") == 0
        or die "cat program failed!";

Which will get the output quickly (as its generated, instead of only at the end ) and also check the return value.

system() also provides direct control over whether shell wildcard processing may take place, whereas backticks do not.