Ubuntu命令行查找文件和字符串：
以查找字符串 isascii 为例：
find -name *.cpp|xargs grep -rnws isascii
find -name *.c|xargs grep -rnws isascii
find -name *.h|xargs grep -rnws isascii
grep -rnws isascii . --include=*.h
grep -rnws isascii . --include=*.cpp
grep -rnws isascii .