LINUXOPOLIS #18 • JAVA

LINUXOPOLIS

A short summary of building a personal Linux environment.
Published with SteemPeak

Screenshot by Willi Glenz

CONTENTS

025 • JAVA                              # NEW
024 • AWK                               
023 • MEMORY                                
022 • ONE-LINER & COWSAY                    
021 • NEOFETCH
020 • VIM
019 • PYTHON
018 • GLANCES
017 • DEBIAN
016 • SCREEN
015 • SHORTCUTS
014 • LINUX-FROM-SCRATCH (LFS)
013 • TOOLBOX
012 • BASHRC
011 • FUZZI FINDER
010 • CRYPTOCURRENCIES
009 • /ETC/FSTAB
008 • ALIASES                                       
007 • RAM-DISK PERMANENT
006 • RAM-DISK TEMPORARY
005 • SOURCES.LIST FOR DEBIAN-STRETCH
004 • SYSTEM UPDATE AND UPGRADE
003 • DCONF-EDITOR                          
002 • GNOME-TWEAK-TOOL                      
001 • VIM-MODE in BASH

025 • JAVA

ORACLE-TUTORIALS

Index               : docs.oracle.com/javase/tutorial/reallybigindex.html
Getting Started     : docs.oracle.com/javase/tutorial/getStarted
Language Basics     : docs.oracle.com/javase/tutorial/java/nutsandbolts/index.html
OOP Concepts        : docs.oracle.com/javase/tutorial/java/concepts/index.html
Classes and Objects : docs.oracle.com/javase/tutorial/java/javaOO/index.html
Annotations         : docs.oracle.com/javase/tutorial/java/annotations/index.html
Interfaces and Inheritance: docs.oracle.com/javase/tutorial/java/IandI/index.html
Numbers and Strings : docs.oracle.com/javase/tutorial/java/data/index.html
Generics            : docs.oracle.com/javase/tutorial/java/generics/index.html
Packages            : docs.oracle.com/javase/tutorial/java/package/index.html
Exceptions          : docs.oracle.com/javase/tutorial/essential/exceptions/index.html
Basic I/O           : docs.oracle.com/javase/tutorial/essential/io/index.html
Concurrency         : docs.oracle.com/javase/tutorial/essential/concurrency/index.html
Platform Environment: docs.oracle.com/javase/tutorial/essential/environment/index.html
Regular Expressions : docs.oracle.com/javase/tutorial/essential/regex/index.html
Collections         : docs.oracle.com/javase/tutorial/collections/index.html
Date & Time         : docs.oracle.com/javase/tutorial/datetime/index.html
Deployment          : docs.oracle.com/javase/tutorial/deployment/index.html
Swing               : docs.oracle.com/javase/tutorial/uiswing/index.html
JavaFX              : docs.oracle.com/javase/8/javase-clienttechnologies.htm
Networking          : docs.oracle.com/javase/tutorial/networking/index.html
Generics            : docs.oracle.com/javase/tutorial/extra/generics/index.html
Internationalization: docs.oracle.com/javase/tutorial/i18n/index.html
JavaBeans           : docs.oracle.com/javase/tutorial/javabeans/index.html
JDBC                : docs.oracle.com/javase/tutorial/jdbc/index.html
RMI                 : docs.oracle.com/javase/tutorial/rmi/index.html
Reflection          : docs.oracle.com/javase/tutorial/reflect/index.html
Security            : docs.oracle.com/javase/tutorial/security/index.html
Sound               : docs.oracle.com/javase/tutorial/sound/index.html
2D Graphics         : docs.oracle.com/javase/tutorial/2d/index.html

SWING

• Bradley Kjell     : chortle.ccsu.edu/java5/Notes/chap55/ch55_1.html
• TutorialsPoint    : tutorialspoint.com/swing/index.htm
• Oracle Trail      : docs.oracle.com/javase/tutorial/uiswing/

JavaFX

• Oracle            : docs.oracle.com/javase/8/javase-clienttechnologies.htm

024 • AWK

$ awk 'BEGIN { print "Don\47t Panic!" }'
$ awk -F: '{ print $1 }' /etc/passwd | sort | tee user.txt
$ awk -F: '$1 == "userxyz" { print $0 }' /etc/passwd
$ awk -F: '/userxyz|root/ { print $0 }' /etc/passwd

INSTALLATION
# apt-get install gawk gawk-doc
$ dpkg -L gawk-doc | less
> file:///usr/share/doc/gawk-doc/gawk-html/index.html#Top

DOKUMENTATION
• Manual            : gnu.org/software/gawk/manual/gawk.html
• Tutorial I        : tutorialspoint.com/awk/index.htm
• Tutorial II       : tldp.org/LDP/abs/html/sedawk.html

023 • MEMORY

SYSTEM-INFORMATION

$ top $ htop $ atop $ glances
$ watch free -h
$ less /proc/meminfo
$ cat /proc/sys/vm/swappiness
# sysctl -a

TROUBLESHOOTING

# sysctl -a
# sysctl vm.swappiness=15
# sysctl -a

# sysctl -a
# bash -c "sync; echo 3 > /proc/sys/vm/drop_caches"
# sysctl -p
# sysctl -a

022 • ONE-LINER & COWSAY

INSTALLATION

$ cp ~/.bashrc ~/.bashrc_old
$ echo 'clear' >> ~/.bashrc
$ echo 'echo' >> ~/.bashrc
$ echo 'neofetch' >> ~/.bashrc
$ echo 'cowsay -W 80 -f moose $(cat ~/bin/oneliner.txt | shuf -n1)' >> ~/.bashrc
$ echo 'echo'
$ . ~/.bashrc

ON-LINER-TEXTFILE

$ vim ~/bin/oneliner.txt
> # bash -c "sync; echo 3 > /proc/sys/vm/drop_caches"
> $ cat /etc/passwd | cut -d: -f7 | sort | uniq -c | sort -nr
> $ cat /etc/shells
> $ curl wttr.in
> $ mkdir -p Backups/{Sales,Development,HR}/{Jan,Feb,Mar,Apr,May,Jun,Jul,Aug,Sep,Oct,Nov,Dec}/{Sun,Mon,Tue,Wed,Thu,Fri,Sat}
> # mkdir -p /mnt/ram; mount -t tmpfs tmpfs /mnt/ram -o size=8192M
> $ mkdir -p dummy/{1..100}/{1..100}
> $ watch -d -n 5 ls -l
> $ watch free -h
:wq

021 • NEOFETCH

$ apt-cache search neofetch
$ apt-cache show neofetch
# apt install neofetch
$ cp ~/.bashrc ~/.bashrc_old
$ \ls -lisa ~/.bashrc*
$ echo "neofetch" >> ~/.bashrc
$ . ~/.bashrc

---
$ inxi -v1

020 • VIM

SOURCES

• Homepage          - vim.org
• Reference         - vimhelp.org/quickref.txt.html
• Documentation I   - vimhelp.org
• Documentation II  - vimhelp.org/usr_toc.txt.html
• FAQ               - vimhelp.org/vim_faq.txt.html
• Wiki              - vim.wikia.com/wiki/Vim_Tips_Wiki
• Bram Moolenaar    - moolenaar.net/habits.html
• Ben McCormick I   - benmccormick.org/2014/06/30/learning-vim-in-2014-the-basics
• Ben McCormick II  - benmccormick.org/2014/07/02/learning-vim-in-2014-vim-as-language
• TutorialsPoint    - tutorialspoint.com/vim/index.htm

INSTALLATION

# apt-get install vim gvim vim-doc vim-scripts 
$ dpkg -L vim-doc
# update-alternatives --config editor
$ vim --version | less

CONFIGURATION

# update-alternatives --config editor
$ vim ~/.bashrc
> EDITOR=/usr/bin/vim
> VISUAL=$EDITOR
> export EDITOR VISUAL

VIMRC

$ vim ~/.vimrc
> syntax on             syntax off
> set nu                nonu
> set relativenumber    norelativenumber

> set cursorline        nocursorline
> set incsearch         noincsearch
> set showmode          noshowmode
> set showcmd           noshowcmd
> set ruler             noruler
> set hls               nohls
> set background=dark
> set encoding=utf8
> set mouse=a

> set autoindent

> set tabstop=3
> set softtabstop=3
> set shiftwidth=3
> set expandtab

> nmap <leader>w :w!<cr>
> map <F2> :echo 'Current time is ' . strftime('%c')<CR>
> map <F5> :set list!<CR>
> map <F6> :setlocal spell! spelllang=en_us<CR>

> :ab psvm public static void main(String[] args) {<CR>}<Esc>ko
> :ab sysout System.out.println("");<Esc>2hi

VIM-SESSION

01  tutorial        $ firefox vim-adventures.com & 
""  tutorial II     $ vimtutor en

02  docu            $ man vim
""  docu II         $ firefox file:///usr/share/doc/vim-doc/html/index.html &
""  docu III        :help user-manual • ^] ^o
""  docu IV         :help edit :help grep ^d ^u

03  buffer          $ ^xe 
""  buffer          :edit
""  buffer          $ vim -O ~/.vimrc ~/.bashrc ^ww ^wr ^wc ^wq
""  buffer          $ vim ~/.bashrc ~/.bashrc :args :ls :next :previous :n :N
""  buffer          :buffers :badd :b1 :b2 :bn :bp :bf :bl

04  motion          ^d ^u  H M L  zz zb zt z<enter> z-  l h j k
05  insert          i I s S a A o O C

06  window          :set nu nonu
""  window          :set relativenumber norelativenumber
""  window          :set hls nohls *
""  window          :set ruler noruler
""  window          :set linebreak nolinebreak
""  window          :call matchadd('colorColumn', '\%81v', 100)
""  window          ^ws ^wv ^wr ^wc ^wq
""  window          gg G ^g 50% ^e ^y ^n ^u ^d ^f ^b

07  repeat          .
08  macro           qa :reg a @a
09  clipboard       vj"+y
10  search          / f * #<br>:set incsearch :nhls

11  change          ~
""  change          :%s/one/two/g
""  change          :set hls <enter> * cw<esc> n :set nohls <enter>
""  change          ci( ci{ ci<

12  delete          x d$ diw dit di" dip das
13  undo redo       u U ^r
14  match           [InsertMode] ^n
15  abbreviate      :ab :abc :unab ^v
16  mark            m1 '1 `1 marks
17  fold            zf5j zo zc zd
18  visual          v ^v
19  text objects    iw it i" ip as f F t T /
99  exit            :wq  :q!  ZZ  ZQ

INSERT MODE

i   : Insert text before the cursor.
I   : Insert text before the first non-blank in the line.
s   : Delete character under the cursor and start insert mode.
S   : Delete line and start insert mode.
a   : Enter insert mode after cursor.
A   : Enter insert mode at the end of the line.
o   : Enter insert mode on the next line.
O   : Enter insert mode on th above line.
C   : Delete from cursor to end of line and begin insert.

TEXT OBJECTS

iw  : inner word
it  : inner tag
i"  : inner quotes
ip  : inner paragraph
i{  : inner brackets
as  : a sentence
f,F
t,T
/

ABBREVIATIONS

:ab psvm public static void main(String[] args) {<CR>}<Esc>ko
:ab sysout System.out.println("");<Esc>2hi
^v      : deaktivate ab

019 • PYTHON

INSTALL ALTERNATIVE
$ python<tab><tab>
$ python --version
# update-alternatives --list python
# update-alternatives --install /usr/bin/python python /usr/bin/python2.7 1
# update-alternatives --install /usr/bin/python python /usr/bin/python3.5 2
# update-alternatives --list python
$ python --version

CHANGE/DELETE ALTERNATIVE
# update-alternatives --config python
# update-alternatives --remove python /usr/bin/python2.7

018 • GLANCES

$ apt-cache search glances
# apt install glances glances-doc
$ apt-cache show glances
$ man glances
$ dpkg -L glances
$ w3m /usr/share/doc/glances/html/quickstart.html

ALTERNATIVE
• Github                            : github.com/nicolargo/glances
# pip install --upgrade glances

017 • DEBIAN

Homepage                : debian.org
Download                : debian.org/distrib/netinst#smallcd
Tutorials               : debiantutorials.com
DistroWatch             : distrowatch.com/table.php?distribution=debian 
w3Tech                  : w3techs.com

Debian News             : debian.org/News
Debian Security         : debian.org/security/#DSAS
Debian Version          $ cat /etc/debian_version

Package Documentation   : /usr/share/doc
Sources List Generator  : debgen.simplylinux.ch 
Debian Backports        : backports.org

DOCUMENTATION

• Documentation         : debian.org/doc

• Installation Guide    : debian.org/releases/stable/amd64/
• Release Notes         : debian.org/releases/stable/amd64/release-notes/
• FAQ                   : debian.org/doc/manuals/debian-faq/
• Wiki                  : wiki.debian.org/FrontPage
• Debian & Java         : debian.org/doc/manuals/debian-java-faq/index.en.html
• Securing Debian       : debian.org/doc/manuals/securing-debian-howto/index.en.html
• Menu System           : debian.org/doc/packaging-manuals/menu.html/ch1.html
• Networking HowTo      : tldp.org/HOWTO/NET3-4-HOWTO.html
• Gnome                 : help.gnome.org

• Reference Card        # apt install debian-refcard
                        $ dpkg -L debian-refcard | less
                        $ w3m /usr/share/doc/debian-refcard/index.html
                        
• Reference             : debian.org/doc/manuals/debian-reference/
                        # apt install debian-reference-en
                        $ dpkg -L debian-reference-en
                        $ w3m /usr/share/doc/debian-reference/docs/index.en.html
                        
• Handbook              : debian.org/doc/manuals/debian-handbook/
                        # apt install debian-handbook
                        $ dpkg -L debian-handbook | less
                        $ w3m /usr/share/doc/debian-handbook/html/en-US/index.html                      

016 • SCREEN

# apt install screen

DOCUMENTATION

$ man screen
$ w3m gnu.org/software/screen/manual/screen.html
• ctrl a?           : Keybindings

SESSIONS

$ screen -S firstsession glances
$ screen -X -S firstsession quit
$ screen -ls        : List screen sessions
$ screen -r         : Reattaching
$ screen -x         : Attach to a not detached screen session
• ctrl ad           : Detach session
• ctrl ax           : Lock session

WINDOWS

• ctrl ac           : Create window
• ctrl aA           : Rename window
• ctrl aa           : Toggle window
• ctrl a[0 .. 9]    : Toggle window
• ctrl a|           : Split window vertically
• ctrl aS           : Split window horizontally
• ctrl aX           : Kill pane
• ctrl an           : Next window
• ctrl ap           : Previous window
• ctrl ak           : Kill window
• ctrl a\           : Kill all windows
• ctrl aw           : Window bar 
• ctrl a"           : Window list
• ctrl ah           : Hardcopy

EXAMPLE

$ screen -S firstsession
• ctrl aS
• ctrl a|
$ htop
• ctrl a<tab>
• ctrl ac
$ atop
• ctrl <tab>
• ctrl ac
$ df -hT

CONFIGURATION
# vim /etc/screenrc
$ vim ~/.screenrc

015 • SHORTCUTS

DAILY USE
• <ctrl>+z fg bg jobs <ctrl>+u <ctrl>+k <ctrl>+w <alt>+. <bash-vim-mode>

CHARACTER
• ctrl f    : Move forward one character
• ctrl b    : Move backward one character
• ctrl h    : Generate a backspace character
• ctrl d    : Delete one character

EDITOR
• ctrl xe   : Editor

DESKTOP
• alt F2    : Run Command

HISTORY
• ctrl r    : Search from history searching mode
• ctrl g    : Escape from history searching mode
• alt .     : Use the last word of the previous command

LINE
• esc #     : Making the line a comment
• ctrl a    : Go to the beginning of the line
• ctrl e    : Go to the end of the line
• ctrl xx   : Move between start of commandline and current position and back again
• ctrl eu   : Clear the line 
• ctrl k    : Delete from cursor to the end of the line
• ctrl u    : Delete from cursor to the start of the line

TERMINAL
$ gnome-terminal
• ctrl alt F3
• reset             : Reset the terminal
• ctrl d or exit    : Exit the terminal
• shutdown -h now   : Shut down the system

SCREEN
• ctrl +-   : Size
• ctrl l    : Clear the screen
• ctrl s    : Stop output to the screen
• ctrl q    : Allow output to the screen

014 • LINUX-FROM-SCRATCH (LFS)

SOURCES

• Homepage          : linuxfromscratch.org/lfs/index.html
• Download          : linuxfromscratch.org/lfs/downloads/stable/
• Online-Book       : linuxfromscratch.org/lfs/view/stable/
• DistroWatch       : distrowatch.com/table.php?distribution=lfs

PROJECTS

• Linux From Scratch            : linuxfromscratch.org/lfs/
• Beyond Linux From Scratch     : linuxfromscratch.org/blfs/
• Automated Linux From Scratch  : linuxfromscratch.org/alfs/
• Cross Linux From Scratch      : trac.clfs.org/

STEPS

03 Virtualbox       : # apt install virtualbox
02 Debian Live-CD   : cdimage.debian.org/debian-cd/current-live/amd64/iso-hybrid/
01 RTFM             : linuxfromscratch.org/lfs/view/stable/

013 • TOOLBOX

# apt install ...
A - alacarte atop aview
B - backintime-qt4 bluefish boostnote
C - calcurse clipit cherrytree cmus
E - espeak 
F - firmware-iwlwifi firmware-realtek focuswriter fzf
G - gdebi gkrellm glances gnome-clocks gnome-do gparted grsync guake 
H - htop hwinfo 
I - inxi i3-wm
K - kismet  
L - libreoffice links lsd lvm2  
M - mc menulibre 
N - netcat net-tools nmap
P - powertop printer-driver-cups 
R - ranger
S - screen sudo syncthing
T - taskwarrior terminator timeshift timewarrior tripwire 
V - veracrypt* vim virtualbox vym 
W - w3m
Y - youtube-dl

012 • BASHRC

$ vim ~/.bashrc
> HISTCONTROL=ignoreboth:erasedups
> alias h='clear; echo; history 30; echo'
> set -o vi
> bind -m vi-insert "\C-l":clear-screen
> EDITOR=/usr/bin/vim
> VISUAL=$EDITOR
> export EDITOR VISUAL

011 • FUZZI FINDER

$ fzf -e --preview 'head -100 {}'

010 • CRYPTOCURRENCIES

$ curl rate.sx
$ curl rate.sx/btc@3d
$ curl rate.sx/steem@3d

009 • /ETC/FSTAB

# blkid
# vim /etc/fstab
> #RAMDISK
> none /media/ramdisk tmpfs nodev,nosuid,noexec,nodiratime,size=1024M 0 0

008 • ALIASES

$ vim ~/.bashrc
> a='clear; echo; alias; echo'
> b='clear; curl rate.sx/btc@3d'
> c='clear; echo'
> cc='clear; ncal -3wy'
> cdh='\cd; clear; echo; lsd -l; echo'
> e='clear; cd ~/Apps; ./eclipse &'
> g='clear; glances'
> h='clear; echo; history 30; echo'
> l='clear; echo; lsd -l; echo'
> ls='clear; echo; lsd -l; echo'
> py='clear; python3'
> r='ranger'
> rs='clear; rsync -avzP --delete --stats --exclude-from "/home/user/.exclude.txt"  /home/user/ /media/backup/'
> s='clear; curl rate.sx/steem@3d'
> ss='clear; curl rate.sx/steem@3d; gnome-screenshot -ac'
> t='clear; task; timew week; timew summary'
> tm='clear; timew month'
> tt='clear; task burndown.daily'
> ttt='clear; task calendar 2019'
> tw='timew'
> u='clear; sudo apt-get update && sudo apt-get upgrade && sudo apt-get dist-upgrade; sudo apt-get autoremove -yy'
:wq

007 • RAM-DISK PERMANENT

# mkdir -p /media/ramdisk
# vim /etc/fstab
> none /media/ramdisk tmpfs nodev,nosuid,noexec,nodiratime,size=1024M 0 0
# mount -a
$ mount | column -t

006 • RAM-DISK TEMPORARY

# mkdir -p /media/ramdisk 
$ mount | column -t
# mount -t tmpfs -o size=1024M tmpfs /media/ramdisk
# mount -a
$ mount | column -t

005 • SOURCES.LIST FOR DEBIAN-STRETCH

• # vim /etc/apt/sources.list

• # Security updates
• deb http://security.debian.org/debian-security stretch/updates main contrib non-free
• deb-src http://security.debian.org/debian-security stretch/updates main contrib non-free

• # Base repository
• deb http://ftp.de.debian.org/debian/ stretch main contrib non-free
• deb-src http://ftp.de.debian.org/debian/ stretch main contrib non-free

• # Stable updates
• deb http://ftp.de.debian.org/debian/ stretch-updates main contrib non-free
• deb-src http://ftp.de.debian.org/debian/ stretch-updates main contrib non-free

• # Stable backports
• deb http://ftp.debian.org/debian stretch-backports main contrib non-free
• deb-src http://ftp.debian.org/debian stretch-backports main contrib non-free

• # Virtualbox
• deb https://download.virtualbox.org/virtualbox/debian stretch contrib

004 • SYSTEM UPDATE AND UPGRADE

alias u='clear; sudo apt-get update && sudo apt-get upgrade && sudo apt-get dist-upgrade; sudo apt-get autoremove -yy'

003 • DCONF-EDITOR

# apt install dconf-editor && apt show dconf-editor
• /org/gnome/terminal/legacy/default-show-menubar

002 • GNOME-TWEAK-TOOL

# apt install gnome-tweak-tool && apt show gnome-tweak-tool
• Typing-Tab > Caps Lock key behaviour > Make Caps Lock an additional ESC|

001 • VIM-MODE in BASH

$ vim ~/.bashrc
• set -o vi
• bind -m vi-insert "\C-l":clear-screen