输出前25行 head -n25 input.txt head -n 25 input.txt head -25 input.txt 输出前5个字符 head -c5 test.cpp head -c 5 test.cpp
参考：
https://www.jb51.net/article/146892.htm
Linux shell head 命令
原文：https://www.cnblogs.com/sea-stream/p/11273659.html
