To refer to trac tickets in commit messages the basic syntax is of the form [command] [ticketreference]. A colon between the command and the ticket reference is allowed. The ticketreference also allows to list multiple ticket numbers separated by spaces and/or comma. The word 'and' is also allowed between ticket numbers. The allowed syntaxes are given below.

To close a ticket from a commit message:
{{{
closes #ticketno
fixes #ticketno
e.g. this closes #10
}}}

To reference a ticket in a commit message:
{{{
addresses #ticketno
re #ticketno
references #ticketno
refs #ticketno
see #ticketno
e.g. this addresses #10 and #25
}}}

A bare reference to a ticket (e.g. !#48) will not trigger a ticket update on trac.

More info on how to use is in the docs: ​https://trac.edgewall.org/wiki/CommitTicketUpdater#Usage