To get the match that you're looking for, use the "+" instead of the "*": 
s/o+/e/;

[download]
will turn "goodwood" into "gedwood" (only the first occurrence is replaced); "+" refers to "one or more". To replace all occurrences of "o+" in the string, use the "g" modifier as well: 
s/o+/e/g;

[download]
will turn "goodwood" into "gedwed".

In reply to Re: Regex - substitute by graff
in thread Regex - substitute by Anonymous Monk

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