Perhaps the documentation for the range operator might throw some light on the subject.

If the left value is greater than the right value then it returns the empty list.

So it looks like it's working exactly as documented.

The Perl documentation is great. You should try reading it :-)

perl -e 'for (reverse 1..5) {print "$_\n"};'

Update: The left operand must be less than the right operand... :(

perl -e 'for (reverse 1..5) { print "$_\n" };'
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Above you have the answer you were looking for. But just out of curiosity, if you use the -l option, you won't need to add those \n to the print statements.

Nor is it necessary to add "$_" to print, for that matter:

perl -le 'for (1..5) { print };'
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Update: And golfing down a little more:

perl -le 'print for(1..5)'
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Nor are the parentheses in this reversed form ;-)

perl -le 'print for 1..5'
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Update: Of course, we could drop for too, but that won't help golfing: perl -le '$,=$/; print 1..5' :)

:o) You are right of course. My intention was not to golf the code. It's just that I find that \n a bit messy, and thus just tried to show something a bit cleaner. But yours are pretty readable as well.

for ($a .. $b) { ... }
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Should be roughly equivalent to

for ($_ = $a; $_ <= $b; $_++) { ... }
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You see that with ($a, $b) = (5, 1) the body of the loop won't be executed. (For strings the comparison is le, not <=, I think).

(update: added ++ where appropriate, Fletch++)

Strange it is, indeed... as others explained, end must be greater than start. You could use negative values to count down:

perl -e 'for (-5..-1) { print -"$_\n" };'
+5
+4
+3
+2
+1
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Leading pluses? Eh. That seems to be perl's way of saying it knows that double negation is affirmation... how strange... but on a second look, one learns that it has to do with the string resulting from the interpolation:

perl -e 'for (-5..-1) { print -$_,"\n" };'
5
4
3
2
1
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A stringified number and a number-number are not always the same thing.. ;-)

_($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}