git diff 文件对比四种情况

工作区和暂存区比较

git diff                  // 当前工作区和暂存区对比
git diff -- <file name>   // 单独文件，当前工作区和暂存区对比

工作区和版本库

git diff HEAD                 // 工作区和版本库对比
git diff HEAD -- <file name>  // 单独文件，工作区和版本库对比
git diff <commitID>           // 工作区和某版本库对比
git diff <commitID> -- <file name>

暂存区和版本库

git diff --cached             // 暂存区和最新版本库
git diff --cached <commitID>  // 暂存区和某版本库
git diff --cached <comitID> -- <fileName>

不同版本库

git diff <commitID> <commitID2>
git diff <commitID> <commitID2> -- <fileName>