Tag: linux

Connecting To Host In A Same Network(LAN) Via SSH

SSH(Secure Shell) is a cryptographic network protocol that allow you to operate network services securely over an unsecured network. There are multiple client in various OS to run ssh. For example, In Linux OpenSSH and in Windows PuTTY is there.
Now suppose you have a home router and there are multiple network connected to it and certainly you want to access a computer from another computer. Let’s take Comp1 wants to connect to Comp2. So, Now you have to create a SSH connection between the computers.

Setting up the SSH Server

So for connection you have to install and start a SSH server in the Comp2 . Let’s see the commands for installing SSH server.

$ sudo apt install openssh-server

Now you have to check SSH service is running or not if not you have to start it.

$ sudo systemctl status ssh

If the status is not showing active in your case the you have to execute the below command 

$ sudo systemctl enable ssh

Get the IP of the Server

We connect to a server by $ ssh user@ip_address so you have figure out the ip address of the Comp2 . And for that you can type ifconfig . Your ip will be something like 192.168.x.y

Enabling SSH traffic on your firewall settings

If you are using UFW as a default firewall on your Ubuntu host, it is likely that you need to allow SSH connections on your host.

To enable SSH connections on your host, run the following command –

$ sudo ufw allow ssh

Then check for firewall has enabled or not –

$ sudo ufw status | grep 22

It should give something like this –

Note : SSH use port 22 by default.

Connecting via SSh

Now go to the Comp2 and type the ssh command followed by the user@ip_address. In my case bellow –

$ ssh aniruddha@192.168.1.5

Then it will prompt for the password and type the password for that user in the computer and here you go your Comp2 terminal will appear in the Comp1 terminal.

Advertisement

Create shared directory in Linux

Sometime we work in a group and we need to access a specific directory or file by multiple user. And in linux we can get this functionality very easily.

Create a common group and directory

We use groupadd command in linux for creating a group. Let’s execute below command and create a group name shared and a directory.

$ mkdir /home/Desktop/shared_directory

$ sudo groupadd shared

Add existing user to the group

We use usermod command to modify an user account in linux. Let’s execute below command to add our existing user aniruddha to the group shared.

$ sudo usermod -a -G shared aniruddha

Set appropriate permission on the directory

By default linux assign the group of a newly created directory or file to it’s current user. But we have to set the group of the directory to shared so that all user in the shared group can access the directory. And we also have to set the setGID so that newly created files or directory inside the shared_directory have the same group as the parent directory.

$ sudo chgrp -R shared /home/Desktop/shared_directory

$ sudo chmod -R 2775 /home/Desktop/shared_directory

Here chgrp is used to change the group of any directory or file and chmod is used to change the permission.
Here -R is recursive operation.
2 is for the setGID.
7 is the rwx permission.
5 is the rx permission.

Create more system users

Now it’s time to create more system user and assign them to the group shared.

$ sudo useradd -m -c "John Doo" -s/bin/bash -G shared john

Now if log in as another user and go to shared_directory you can access it.

Write your commit message in your favourite text editor

Most of us use git as their version control system and in day to day life while developing any application we commit our changes quite frequently. We follow the traditional way of committing changes like below –

$ git commit -m "Our commit message"

But we have another cool option to do this commit. We can use our favorite text editor for this commit. We have to first tell git that pop up the text editor every time you commit changes. For this execute below command in your terminal –

$ git config --global core.editor "vim"

Here it will pop up the vim text editor when you will execute git commit.

Thank you 🙂

Customize your vim like any other IDE

So, almost 2 years ago I heard about C programming language from my close friend and I thought I should give it a try and I asked “how can I start with it?” and he gave me some notes and said just install turboC++ and start writing code. So, I installed it and started with C language and eventually I got demotivated and quit programming after some time. Actually it was not fun and engaging with that environment. After one year in my college their was a seminar of network security and the guest speaker said that everyone should try python once and it is really amazing language. And I went home and searched for the python in the YouTube and found lots of tutorial on it and picked up one and that tutorial is using VSCode after that I loved that text editor and still I use it in my daily work.

In my recent days I got to know about a new text editor called vim and I recently installed and start using it. The most funny thing is when I first open a file with it I was not able to exit from it :p. Now I use it in most of the time while writing code. When you will first install it then it will look something below like this

The vim allow us to customize it however we want and we customize it by writing some code in the ~/.vimrc and if the file is not there you can add it by doing touch ~/.vimrc command. Now add below line to your file first.

syntax enable

set shell=/bin/bash

set tabstop=4
set shiftwidth=4
set expandtab
set number
set autoindent
set ruler
set showcmd
set hlsearch
set wrap
set linebreak
set noswapfile
set incsearch
set nohlsearch
set ignorecase
set smartcase
set showmatch
set showmode
set cursorline
set title
set clipboard=unnamedplus
set encoding=UTF-8

set nocompatible

set background=dark
set termguicolors

Now we will add some plugins in this file and then we are going to install it.There are couple of ways to install plugins and the way i like is by Vundle And the section below shows how to add plugins .

set rtp+=~/.vim/bundle/Vundle.vim
call vundle#begin()

Plugin 'VundleVim/Vundle.vim'
Plugin 'scrooloose/nerdTree' "Documents tree
Plugin 'davidhalter/jedi-vim' "python autocompletion
Plugin 'scrooloose/syntastic' "code syntaxis
Plugin 'Raimondi/delimitMate' "automatic closing of quotes, parenthesis...
Plugin 'yggdroot/indentline' "Show indent lines (useful for loops)
Plugin 'vim-airline/vim-airline'
Plugin 'vim-airline/vim-airline-themes'
Plugin 'ervandew/supertab' "<Tab> for code completion
Plugin 'jistr/vim-nerdtree-tabs'
Plugin 'ntpeters/vim-better-whitespace'
Plugin 'sjl/badwolf'
Plugin 'python/black'
Plugin 'andviro/flake8-vim'
Plugin 'fatih/vim-go'
Plugin 'tpope/vim-commentary'
Plugin 'airblade/vim-gitgutter'
Plugin 'jreybert/vimagit'
Plugin 'ryanoasis/vim-devicons'

call vundle#end()

autocmd BufWritePre *.py execute ':Black'
let g:black_linelength = 79

let g:PyFlakeOnWrite = 1
let g:PyFlakeCheckers = 'pep8,mccabe,frosted'
let g:PyFlakeDefaultComplexity=10
let g:PyFlakeDisabledMessages = 'E1101,C0111,E1136,W0703,C0103,C0330,W504'
let g:PyFlakeAggressive = 0
let g:PyFlakeCWindow = 6
let g:PyFlakeSigns = 1
let g:PyFlakeSignStart = 1
let g:PyFlakeForcePyVersion = 3

filetype plugin indent on

colorscheme badwolf


" Go syntax highlighting
let g:go_highlight_fields = 1
let g:go_highlight_functions = 1
let g:go_highlight_function_calls = 1
let g:go_highlight_extra_types = 1
let g:go_highlight_operators = 1

" Go preview disable
set completeopt-=preview

" Auto formatting and importing
let g:go_fmt_autosave = 1
let g:go_fmt_command = "goimports"

" Status line types/signatures
let g:go_auto_type_info = 1

" Run :GoBuild or :GoTestCompile based on the go file
function! s:build_go_files()
  let l:file = expand('%')
  if l:file =~# '^\f\+_test\.go$'
    call go#test#Test(0, 1)
  elseif l:file =~# '^\f\+\.go$'
    call go#cmd#Build(0)
  endif
endfunction

" Map keys for most used commands.
" Ex: `\b` for building, `\r` for running and `\b` for running test.
autocmd FileType go nmap <leader>b :<C-u>call <SID>build_go_files()<CR>
autocmd FileType go nmap <leader>r  <Plug>(go-run)
autocmd FileType go nmap <leader>t  <Plug>(go-test)

au filetype go inoremap <buffer> . .<C-x><C-o>

" NERDTree setup
map <C-z> :NERDTreeToggle<CR> “ Toggle side window with `CTRL+z`.
let g:NERDTreeDirArrowExpandable = '▸'
let g:NERDTreeDirArrowCollapsible = '▾'
let NERDTreeShowHidden=1 " Show hidden files

" Vim airline
let g:airline_powerline_fonts=1
let g:airline#extensions#tabline#enabled = 1
let g:airline#extensions#tabline#left_sep = ' '
let g:airline#extensions#tabline#left_alt_sep = '|'
let g:airline#extensions#tabline#formatter = 'default'

" Git Gutter
" Use fontawesome icons as signs
let g:gitgutter_sign_added = '+'
let g:gitgutter_sign_modified = '>'
let g:gitgutter_sign_removed = '-'
let g:gitgutter_sign_removed_first_line = '^'
let g:gitgutter_sign_modified_removed = '<'

let g:gitgutter_override_sign_column_highlight = 1
highlight SignColumn guibg=bg
highlight SignColumn ctermbg=bg

set updatetime=250

nmap <Leader>gn <Plug>GitGutterNextHunk  " git next
nmap <Leader>gp <Plug>GitGutterPrevHunk  " git previous
nmap <Leader>ga <Plug>GitGutterStageHunk  " git add (chunk)
nmap <Leader>gu <Plug>GitGutterUndoHunk   " git undo (chunk)

" Open vimagit pane
nnoremap <leader>gs :Magit<CR>       " git status

" Move between buffers
map gn :bn<cr>
map gp :bp<cr>
map gd :bd<cr>

" Move line up and down
nnoremap K :m .-2<CR>==
nnoremap J :m .+1<CR>==
vnoremap K :m '<-2<CR>gv=gv
vnoremap J :m '>+1<CR>gv=gv

" Set Ctrl+h for highlight search
nnoremap <c-h> :set hlsearch!<cr>

" Disable K for documentation of go and py
let g:go_doc_keywordprg_enabled = 0
let g:jedi#documentation_command = 0

That’s how we add Plugins to the vim by writing Plugin and after that what plugin we want to install. Now to install plugins first type Esc then : and after that type PluginInstall then press enter and all the plugins will install one by one.

Now vim is looks something like blow image.

Thank you 🙂