–extra = f选项告诉ctags：
“Include an entry for the base file name of every source file (e.g. “example.c”),which addresses the first line of the file.” @H_404_10@ 打开vim时,可以使用：tag< filename>跳到文件的第一行.
“Include an entry for the base file name of every source file (e.g. “example.c”),which addresses the first line of the file.”
打开vim时,可以使用：tag< filename>跳到文件的第一行.
