/Out (devenv.exe)
Visual Studio 2012
Specifies a file to store and display errors when you run, build, rebuild, or deploy a solution.
devenv /out FileName
If a file name that does not exist is specified, the file is created automatically. If the file already exists, the results are appended to the existing contents of the file.
Command line build errors are displayed in the Command window and the Solution Builder view of the Output window. This option is useful if you are running unattended builds and need to see the results.