That won't work. What he needs is a positive look-ahead assertion, like this: 
use strict;
$_ = "|90|93|foo|bar|91|92|95|96|906|";
s{
    \|9
    [0-6]+
    (?=\|)
}
{|X}xg;
print $_,"\n";

[download]
You also can't use 'x' mode to ignore whitespace in the replacement part. I also fixed that.

In reply to Re: Re: Replacing consecutive tokens in 1 pass by tall_man
in thread Replacing consecutive tokens in 1 pass by aarestad

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