https://www.runoob.com/linux/linux-comm-grep.html https://www.tutorialspoint.com/unix_commands/grep.htm https://www.geeksforgeeks.org/fold-command-in-linux-with-examples/
每日一题 https://github.com/WindrunnerMax/EveryDay 参考 https://www.runoob.com/linux/linux-comm-grep.html https://www.tutorialspoint.com/unix_commands/grep.htm https://www.geeksforgeeks.org/fold-command-in-linux-with-examples/