‘nuget.exe update‘ and ‘Install-Package‘ now both have a new option ‘-FileConflictAction‘ to set some default for command-line scenarios.+
Set a default action when a file from a package already exists in the target project. Set to ‘Overwrite‘ to always overwrite files. Set to ‘Ignore‘ to skip files. If not specified, it will prompt for each conflicting file.
nuget update FileConflictAction
原文：http://www.cnblogs.com/atuo/p/6904803.html