hg parents [-r REV] [FILE]

show the parents of the working directory or revision

    Print the working directory's parent revisions. If a revision is given via
    -r/--rev, the parent of that revision will be printed. If a file argument
    is given, the revision in which the file was last changed (before the
    working directory revision or the argument to --rev if given) is printed.

    Returns 0 on success.


 -r --rev REV           show parents of the specified revision
    --style STYLE       display using template map file
    --template TEMPLATE display with template

use "hg -v help parents" to show more info