Current Perl documentation can be found at perldoc.perl.org.
Here is our local, out-dated (pre-5.6) version:
Strictly speaking, nothing. Stylistically speaking, it's not a good way to write maintainable code because backticks have a (potentially humungous) return value, and you're ignoring it. It's may also not be very efficient, because you have to read in all the lines of output, allocate memory for them, and then throw it away. Too often people are lulled to writing:
`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:
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.