As a first idea, awk:

awk -vRS='#[^#]+#' 'RT{gsub(/#/,"",RT);p[RT]=1}END{for(i in p)print i}' the_file

But this decision may depend on the other operations you have to perform.

As a first idea, awk:

awk -vRS='#[^#]+#' 'RT{gsub(/#/,"",RT);p[RT]=1}END{for(i in p)print i}' the_file

But this decision may depend on the other operations you have to perform.

Explanations as requested in comment.

awk -vRS='#[^#]+#' '   # use /#[^#]+#/ as record separator
RT {   # record terminator not empty?
  gsub(/#/,"",RT)    # remove the # parameter delimiter markup
  p[RT]=1   # store it as key in array p
}
END {   # end of input?
  for (i in p) print i   # loop through array p and print each key
}' the_file

The essential part is the use of RT (record terminator) built-in variable:

   RT          The record terminator.  Gawk sets RT to the input text that
               matched the character or regular expression specified by
               RS.