Record some Linux operation command (1)

1. mkdir
   mkdir -vp shiyanlou/{lib/,bin/,doc/{info,product}}
   you can create serveral directories with regular expression {};
   -v verpose
   -p parent
2. rm
3. mv
   rename shiyanlou.log as zhou.log: mv shiyanlou.log zhou.log
   move, and the target directory must exit or it will be renamed as test: mv shiyanlou.log test
4. cp
   create a symbolic link: `cp -s shiyanlou.log zhou.log
5. cat(concatenate)
   transplant the content in shiyanlou.log to zhou.log with line number: cat -n shiyanlou.log > zhou.log
   -s --squeeze-blank, compress the multi-blank line to single blank line
   how to show serveral lines content in the interaction panel

shiyanlou:~/ $ cat -A << EOF                                         [23:48:21]
heredoc> 'ls -l'
heredoc> EOF
'ls -l'$

6. nl
   numerate lines: nl -b t shiyanlou.log
   -b 指定行号指定的方式，主要有两种：
   -b a 表示不论是否为空行，也同样列出行号(类似 cat -n)
   -b t 如果有空行，空的那一行不要列出行号(默认值)