golang regex get the string including the search character

I am extracting a piece of string from a string (link):

https://arteptweb-vh.akamaihd.net/i/am/ptweb/100000/100000/100095-000-A_0_VO-STE%5BANG%5D_AMM-PTWEB_XQ.1V7rLEYkPH.smil/master.m3u8 

The desired output should be 100000/100000/100095-000-A_

I am using the Regex ^.*?(/[i,na,fm,d]([,/]?)(/am/ptweb/|.+=.+,))([^_]*).*?$ in Golang flavor and I can get only the group 4 with the folowing output 100000/100000/100095-000-A

However I want the underscore after A.

Bit stuck on this, any help on this is appreciated.

You can use

(/(i|na|fm|d)(/am/ptweb/|.+=.+,))([^_]*_?)

See the regex demo.

Details:

• (/(i|na|fm|d)(/am/ptweb/|.+=.+,)) - Group 1:
  • / - a / char
  • (i|na|fm|d) - Group 2: i, na, fm or d
  • (/am/ptweb/|.+=.+,) - Group 3: /amp/ptweb/ or one or more chars as many as possible (other than line break chars), =, one or more chars as many as possible (other than line break chars) and a , char
• ([^_]*_?) - Group 4: zero or more chars other than _ and then an optional _.

You can match the underscore after the A like:

^.*?(/(?:[id]|na|fm)([,/]?)(/am/ptweb/|.+=.+,))([^_]*_).*$

See a regex demo

A few notes about the pattern that you tried:

• This notation is a character class [i,na,fm,d] which should be a grouping (?:[id]|na|fm)
• In this group ([,/]?) you optionally capture either , or / so in theory it could match a string that has /i//am/ptweb/
• The last part .*?$ does not have to be non greedy as it is the last part of the pattern
• This part [^_]* can also match spaces and newlines