Feature/quickstart commandline

doc/quickstart/commandline_quickstart.rst

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+:Author: Astrid Emde
+:Author: Enock Seth Nyamador
+:Version: osgeolive14.0
+:License: Creative Commons Attribution-ShareAlike 3.0 Unported  (CC BY-SA 3.0)
+
+********************************************************************************
+Command Line Quickstart
+********************************************************************************
+
+When you work with the linux operations systems it is good to know how to work on the command line. 
+
+Don't worry. It is not difficult to learn and you will discover that it is fun and very powerful.
+
+In this quickstart you will learn some basic commands.
+
+The following commands run from within a Terminal Emulator window.
+
+Start a Terminal Emulator (QTerminal currently) from the Applications menu in the System Tools section. This gives you a Unix shell command prompt.
+
+.. contents:: Contents
+   :local:
+
+
+Where am I?
+==========================
+
+pwd shows the path of your actual location.
+
+:: 
+
+ pwd
+ /home/user
+
+
+.. tip:: 
+   You can ask all commands for help and get information on how they can be used and find out about additional options.
+
+
+:: 
+
+
+  pwd --help
+  pwd: pwd [-LP]
+    Print the name of the current working directory.
+
+    Options:
+      -L        print the value of $PWD if it names the current working
+                directory
+      -P        print the physical directory, without any symbolic links
+
+    By default, `pwd' behaves as if `-L' were specified.
+
+    Exit Status:
+    Returns 0 unless an invalid option is given or the current directory
+    cannot be read.
+
+
+
+How to navigate in the file system?
+===================================
+
+First you should get to know how the file system under Linux is organized. The file system is organized in a tree. It starts with the / (root) directory. All files and directories are under the root directory /.
+
+Your user user has a home directory located at /home/user. When you open a terminal window you will start in your home directory (see pwd).
+
+You can easily navigate in the file system with the command cd.
+
+cd / navigated to the root directory 
+cd /home/user goes to your home directory
+same as
+cd ~
+
+cd .. goes on directory to the top
+cd user goes from your current location to the directory user. This is not the same as /user
+
+.. tip:: 
+   Use the tab key to autocomplete the path while you are writing. 
+
+
+Create a directory
+==================
+
+You have write access in your user-directory. You can create files and directories there. Next we will create a directory for some command line tests.
+
+:: 
+
+ cd ~
+ mkdir demo - creates the directory demo 
+ cd demo
+
+.. tip:: 
+   You have a command history. You can navigate in the history with the arrow up and down key.
+
+
+How to create a new file
+=========================
+
+touch creates a new empty file.
+
+:: 
+
+ cd ~/demo
+ touch hello.txt
+
+.. tip:: 
+   You can pipe the information from a command to a file f.e. the command history. history displays the command history. With the following command it can be saved in a file.
+
+::
+
+ history > history.txt
+
+
+Show me what is in a directory
+==============================
+
+You would like to know more about the content in a directory. ls is the program that gives you a lot of information.
+
+* ls lists all files and directories
+* ls -l shows a more detailed list of the files/directories with time, user access rights
+* ls -a also shows hidden files
+* ls -al you can combine the different options
+* ls -1 shows only the file names
+
+:: 
+
+ cd ~/demo
+ ls -l
+
+ total 4
+ -rw-rw-r-- 1 user user   0 Dec 26 16:23 hello.txt
+ -rw-rw-r-- 1 user user 255 Dec 26 16:24 history.txt
+
+
+
+
+Copy files and directories
+==========================
+
+You can copy files from one location to another.
+
+
+Copy a file to a new file
+
+:: 
+
+ cp hello.txt hello_again.txt
+
+
+Copy a file to another directory
+
+:: 
+
+ cp hello.txt /home/user/ 
+
+
+Copy a whole directory to a new location (-R recursive)
+
+:: 
+
+ cp -R /home/user/demo /tmp 
+
+
+
+Who is sudo?
+============
+
+With sudo you can do things that you are normally not allowed to.
+sudo runs commands with the rights of the superuser root
+With sudo you can f.e. install more software, administrate services, change access rights and more fun. You will see the use of sudo in some of the following commands.
+
+
+Search and install programs
+============================
+
+Show information about programs.
+
+:: 
+
+ apt show postgis
+
+Search for programs 
+
+:: 
+
+ apt search postgis
+
+
+Install programs
+
+:: 
+
+ sudo apt-get install sl
+
+
+You will love the program sl. Run the new program with sl see also apt show sl.
+
+
+Services
+========
+
+Some programms run as services like PostgreSQL, tomcat or Apache Webserver. You can start or stop the services.
+
+Restart your Apache Service
+
+:: 
+
+ sudo service apache2 restart
+
+ sudo service apache2 --help
+
+ sudo service apache2 status
+
+
+How to edit files
+=================
+
+You can either edit files in the terminal or open them with an external program like geany.
+
+In the terminal window you can use the vim editor (Vi IMproved). vim is very powerful and has many options.
+
+See also 
+* https://help.ubuntu.com/community/VimHowto
+* https://vim.rtorr.com/lang/en_en
+
+
+Open a file with vim:
+
+:: 
+
+ vim /home/user/demo/hello.txt
+
+* press i to switch to the edit mode
+* ESC leave the edit mode
+* :w save your changes
+* :wq save your changes and close the file
+* :q close the file
+* :q! close the file without saving
+
+
+
+Owner and access rights
+=======================
+
+Access rights define whether a user or group or others have access to a file and what sort of access is given. You can have read, write or excecute access.
+
+Directories or files have an owner and a group definition. By default the creator of a file/directory is the owner. But this definition can get changed. You will learn this in the next section.
+
+You can show the user and group via ls -l
+
+:: 
+
+ cd /home/user/demo
+ ls -l
+ -rw-rw-r-- 1 user user 122 Dec 26 16:11 history.txt
+
+* the initial character can be - for a file or d for directory
+* user is defined as the owner and the group
+
+Access rights are listed at the beginning of the row:
+* r read
+* w write
+* x execute
+
+* first 3 letters for the owner
+* then 3 letters for the group
+* followed by 3 letters for others 
+
+
+You can change the owner with chown
+===================================
+
+:: 
+
+ sudo chown -R user:www-data /var/www/html/TBD
+
+* first pass the user than the group - like user:www-data
+* -R recursive
+
+
+You can change the access rights with chmod
+===========================================
+
+:: 
+
+ sudo chmod -R 777 /var/www/html/TBD 
+
+
+* 777 everyone can do everything
+* -R recursive
+
+* 1. number: owner (u) 
+* 2. number: group (g)
+* 3. number: other (o)
+
+* 4 read
+* 2 write
+* 1 execute
+
+* 660 user and group are allowed to read and write, other have no rights
+* 744 user can do everything, group and others can only read
+
+or use it like this
+
+:: 
+
+ sudo chmod -R u+rwx /var/www/html/TBD 
+
+* u = user 
+* g = group 
+* o = other 
+* a = all 
+* +/- right: r = read / w = write / x = execute
+
+
+Things to try
+=============
+
+Here are other commands you may try.
+
+* grep - search for a pattern in a text
+* history | grep cd
+* rm - remove a file/directory
+* mv - rename
+* less - show the beginning of a file
+* tail - show the end of a file
+* find
+* locate
+
+
+
+What next?
+==========
+
+You learned some important commands and information to work on the command line. Hopefully you discovered how powerful the command line is.
+
+* https://ubuntu.com/tutorials/command-line-for-beginners#1-overview
+* https://en.wikipedia.org/wiki/Category:Standard_Unix_programs
+
+
+