This

  1 while s/^FOO/BAR/g;

repeats the substitution till it fails¹ ...

...which doesn't make much sense because of the ^ anchoring at the start, i.e. it can't substitute more than once.

This should lead to the same results 

while (<FH>) {
  s/^FOO/BAR/;
  print "$_";
}

[download]

The rest (iterating over lines from filehandle with $_) should be obvious, right?

If not have a look at perlintro

Cheers Rolf

PS: Je suis Charlie!

update
¹) it's a postfix equivalent of

while (s/^FOO/BAR/g) {
    1 ; # no op
}

[download]

In reply to Re: Different way to use while loop by LanX
in thread Different way to use while loop by ChuckP

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