I found that perl actually don't return the same scalar...

Doubtful. Can you copy/paste the output?

Or better still, a patch , something along the lines of 

$ diff -ruN tmp.empty tmp.full
diff -ruN tmp.empty/1 tmp.full/1
--- tmp.empty/1 1969-12-31 16:00:00.000000000 -0800
+++ tmp.full/1  2011-06-23 02:46:59.875000000 -0700
@@ -0,0 +1 @@
+ECHO is on.
diff -ruN tmp.empty/2 tmp.full/2
--- tmp.empty/2 1969-12-31 16:00:00.000000000 -0800
+++ tmp.full/2  2011-06-23 02:47:01.312500000 -0700
@@ -0,0 +1 @@
+ECHO is on.

[download]
so that we may compile code try the same code as you :)

In reply to Re^3: What does perl stack OPs really do? by Anonymous Monk
in thread What does perl stack OPs really do? by llancet

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