az sig --help Manage shared image gallery.

addaxnasom

Group
    az sig : Manage shared image gallery.

Subgroups:
    image-definition : Create an image definition.
    image-version    : Create a new version from an image defintion.

Commands:
    create           : Create a share image gallery.
    delete           : Delete a Shared Image Gallery.
    list             : List share image galleries.
    show             : Retrieves information about a Shared Image Gallery.
    update           : Update a share image gallery.