Regular expression to extract text between multiple hyphens

The pattern matches the whole line except the first and last hyphen due to the assertions on the left and right and the . also matches a hyphen.

You can keep using the assertions, and match any char except a hyphen using [^-]+ which is a negated character class.

(?<=-)[^-]+(?=-)

See a regex demo.

Note: if you also want to prevent matching a newline you can use (?<=-)[^-\r\n]+(?=-)

With your shown samples please try following regex.

^-+([^-]*)-+$

Online regex demo

Explanation: Matching all dashes from starting 1 or more occurrences then creating one and only capturing group which has everything matched till next - comes, then matching all dashes till last of value.

You are using Python, right? Then you do not need regex.

Use

s = "----------some text-------------"
print(s.strip("-"))

Results: some text.

See Python proof.

With regex, the same can be achieved using

re.sub(r'^-+|-+$', '', s)

See regex proof.

EXPLANATION

--------------------------------------------------------------------------------
  ^                        the beginning of the string
--------------------------------------------------------------------------------
  -+                       '-' (1 or more times (matching the most
                           amount possible))
--------------------------------------------------------------------------------
 |                        OR
--------------------------------------------------------------------------------
  -+                       '-' (1 or more times (matching the most
                           amount possible))
--------------------------------------------------------------------------------
  $                        before an optional \n, and the end of the
                           string