hg update [-c] [-C] [-d DATE] [[-r] REV]

aliases: up, checkout, co

update working directory (or switch revisions)

    Update the repository's working directory to the specified changeset. If
    no changeset is specified, update to the tip of the current named branch
    and move the current bookmark (see "hg help bookmarks").

    If the changeset is not a descendant of the working directory's parent,
    the update is aborted. With the -c/--check option, the working directory
    is checked for uncommitted changes; if none are found, the working
    directory is updated to the specified changeset.

    Update sets the working directory's parent revison to the specified
    changeset (see "hg help parents").

    The following rules apply when the working directory contains uncommitted
    changes:

    1. If neither -c/--check nor -C/--clean is specified, and if the requested
       changeset is an ancestor or descendant of the working directory's
       parent, the uncommitted changes are merged into the requested changeset
       and the merged result is left uncommitted. If the requested changeset
       is not an ancestor or descendant (that is, it is on another branch),
       the update is aborted and the uncommitted changes are preserved.
    2. With the -c/--check option, the update is aborted and the uncommitted
       changes are preserved.
    3. With the -C/--clean option, uncommitted changes are discarded and the
       working directory is updated to the requested changeset.

    Use null as the changeset to remove the working directory (like "hg clone
    -U").

    If you want to revert just one file to an older revision, use "hg revert
    [-r REV] NAME".

    See "hg help dates" for a list of formats valid for -d/--date.

    Returns 0 on success, 1 if there are unresolved files.

options:

 -C --clean     discard uncommitted changes (no backup)
 -c --check     update across branches if no uncommitted changes
 -d --date DATE tipmost revision matching date
 -r --rev REV   revision

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