gavin0123的专栏

1.行首与行尾字符^$ 行首: oyzhx@ubuntu:~$ grep -n '^the' regular_express.txt 12:the symbol '*' is represented as start. 行尾 oyzhx@ubuntu:~$ grep -n '\.$' regular_express.txt 1:"Open Source" is a good m

1.双引号仍然可以保有变量的内容，单引号内jing