devenv.exe与devenv.com

上星期在做visual studio自动构建的时候，突然发现build过程的日志没有在命令行输出，这样子一旦build失败，就看不到错误原因了。奇怪的是以前是可以看到这些日志的。先后怀疑了CMakeList.txt，构建脚本后，终于发现脚本中有一句devenv solution.sln /rebuild被改成了devenv.exe solution.sln /rebuild 。诱因找到了，背后的原理何在？MSDN的这个页面有很好的说明，Devenv Command Line Switches。

The devenv.com utility provides for the delivery of output through standard system streams, such as stdout and stderr, and determines the appropriate I/O redirection when it captures output, for example, to a .txt file. Commands that begin instead with devenv.exe can use the same switches, but will send them to the devenv.exe program, bypassing the devenv.com utility.

可以看到，由于多余的加了exe，日志就没有被转发到标准输出上了。