sujet shellscripting

Module : B-SHL-400
Repository name : SHL_$YEAR_shell ($YEAR=2017 for 2017/2018)
Repository rights : ramassage-tek
Language : /bin/sh or /bin/bash
Group Size : 1-2
Authorized binary : /!\ See end of this file ! /!\
Yammer Group : PSH $PROMO

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Warning : for all scripts, error messages must be send on stderr output, and
program exit with error code 1 when error
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Update 23/01/2018 - 10:35
Before update :
  ./bdsh -f file.json insert user id=4,firstname=Robert John,lastname=WILLIAMS
After update :
  ./bdsh -f file.json insert user id=4,firstname=Robert\ John,lastname=WILLIAMS
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Subject:
  Write a shell script that allows you to manage a database in a json file.
  You must create table, insert-update-remove data, run query, ...

Database File:
  The database file can be specified in 3 ways, in order of priority:
	as argument in command line : -f file
    in environment : BDSH_File=
    in a configuration file : .bdshrc

Program must display error when :
	Syntax error in command line (bad arguments, ...)
	Database already exist when create database
	Can't create database (disc full, ...)
	Table already exist when create table
	Table not found when select, insert, ...
	Fields not found when select, insert, ...
	Select on empty database
	...

Syntax:
$> ./bdsh
Usage: ./bdsh [OPTION]... [COMMAND] [REQUEST]
OPTION:
  -h				display usage
  -f FILE			json database file
  -j                json formated output for select command

COMMAND and REQUEST:
	create		create database
			Exemple:
				./bdsh -f file.json create database
				./bdsh -f file.json create table user id,firstname,lastname
				./bdsh -f file.json create table age id,age

	insert		insert data in database
			Exemple:
				./bdsh -f file.json insert user id=1,firstname=John,lastname=SMITH
				./bdsh -f file.json insert user id=4,firstname=Robert\ John,lastname=WILLIAMS
				./bdsh -f file.json insert user id=2,firstname=Lisa,lastname=SIMPSON
				./bdsh -f file.json insert user id=10,lastname=SMITH
				./bdsh -f file.json insert user firstname=Laura,lastname=SMITH
				./bdsh -f file.json insert user id=9
				./bdsh -f file.json insert age id=1,age=42

	describe      describe table structure
			Exemple:
				./bdsh -f file.json describe user
				id
				firstname
				lastname

	select		display data from database
			Exemple:
				./bdsh -f file.json select user firstname,lastname
				firstname    | lastname
				-------------------------
				John         | SMITH
				Robert John  | WILLIAMS
				Lisa         | SIMPSON
				             | SMITH
				Laura        | SMITH
				             |
				./bdsh -f file.json select user lastname,firstname order
				lastname  | firstname
				-------------------------
				          |
				SIMPSON   | Lisa
				SMITH     |
				SMITH     | John
				SMITH     | Laura
				WILLIAMS  | Robert John

File Format :
	Database file is a json file correctly formated.
	Json file must contain 2 arrays for a table :
		desc_$table : array with field list of table
		data_$table : array with list : field:value
		see sample.json in subject directory

Shell:
	Shell must be /bin/sh or /bin/bash (#shebang)

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Authorized binary :
  * expr
  * wc
  * head
  * tail
  * cat
  * sort
  * grep
  * sed
  * cut
  * tr
  * touch

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Bonus :
		Add many query, join, where, ...

		Exemple:

				./bdsh -f file.json select user,age age,firstname,lastname join id where age=42
				age  | firstname  | lastname
				------------------------------
				42   | John       | SMITH

				./bdsh -f file.json update user firstname=Marry where firstname=John
				./bdsh -f file.json update user lastname=DAVIS,firstname=Marge where id=9

				./bdsh -f file.json delete user where lastname=SMITH
				3 row(s) deleted

				./bdsh -f file.json select user firstname,id where lastname=SMITH
				firstname  | id
				-----------------
				John       | 1
				           | 10
				Laura      |

				./bdsh -f file.json select user firstname, lastname where lastname=SMITH order
				firstname  | lastname
				-----------------------
				           | SMITH
				John       | SMITH
				Laura      | SMITH