I am very new to programming, and I suspect the answer to this will be laughably obvious, but here goes: I want to use regular expressions to find and replace all occurrences of a string in an entire file. In the Q&A section I found a snippet to find a string in a file: 
{
    open(FILE, "sample.txt") or die "Can't open sample.txt\n";
    local $/ = undef;
    $lines = <FILE>;
    close(FILE);
}
if($lines =~ /foo/) {
print "A match was found\n"
}

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All very well and good. But how do I replace "foo" with "bar"? I tried this: 
$lines =~ s/foo/bar/gms;

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but it doesn't do anything to the other file. Help! Thank you!

In reply to Regex to find/replace in a file by amarceluk

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