notes about bash script

###shell 常见符号解释

2013/12/05 add some basic bash script, know a word shebang or we can simple say #!/bin/sh in the header of script file! It's a interpreter directive

2013/12/07 add notes about case and if

2013/12/11 add notes about

select   
   --  do   command...  
break  
done  

2013/12/22 add some examples about `variable assignment`

2013/12/26 add example about `position parameter and shift_use`

2013/12/27 add example `quote_variable.sh`

2013/12/29 add example `escape`

2014/1/2 add example about `exist status`

2014/1/3 add example about `test construct`

2014/1/7 add example about `file-test-operators`