Re: Substitution of a particular letter in all combinations of positions in word (see inside)

  DB<182> $s=join '{e,a}',split /e/,"ferber"
 => "f{e,a}rb{e,a}r"

  DB<183> @a=< $s >
 => ("ferber", "ferbar", "farber", "farbar")
[download]

UPDATE

one-liner

  DB<192> @a=glob(join '{e,a}',split /e/,"ferber")
 => ("ferber", "ferbar", "farber", "farbar")
[download]

Cheers Rolf