Favorite Linux: Shell Aliases -- gitupdate

 I hope you love these as much as I do.  Here are a few of my favorite aliases (ref: man alias):

1.    Git Update

    Personally, I like to update (commit) my work frequently and often.  Many moons ago, when God was still a baby, we used WordPerfect on the mono-chrome Wyse terminal.  Too often, our documents were completely lost before completion, and it was always our own damn fault because we hadn't saved our work frequently enough.  This brings us back to habit #1 and today.  Now we use Git/GitLab to save much of our work (also from a terminal).  

    To save work (commit) there are 3 commands which perform: 1) add new files, 2) save the state with a message (what you did), and 3) upload to the central repository.  While the message is important for collaboration with other team members, it's not necessary for solo work.  This macro conserves time, encourages you to save, and includes the relevant info needed (whodunit, hostname, and time of day).  We find it informative and time saving.

256 color directory listing

 LS_COLORS='rs=0:di=01;34:ln=01;36:mh=00:pi=40;33:so=01;35:do=01;35:bd=40;33;01:cd=40;33;01:or=40;31;01:mi=00:su=37;41:sg=30;43:ca=30;41:tw=30;42:ow=34;42:st=37;44:ex=01;32:*.tar=01;31:*.tgz=01;31:*.arc=01;31:*.arj=01;31:*.taz=01;31:*.lha=01;31:*.lz4=01;31:*.lzh=01;31:*.lzma=01;31:*.tlz=01;31:*.txz=01;31:*.tzo=01;31:*.t7z=01;31:*.zip=01;31:*.z=01;31:*.dz=01;31:*.gz=01;31:*.lrz=01;31:*.lz=01;31:*.lzo=01;31:*.xz=01;31:*.zst=01;31:*.tzst=01;31:*.bz2=01;31:*.bz=01;31:*.tbz=01;31:*.tbz2=01;31:*.tz=01;31:*.deb=01;31:*.rpm=01;31:*.jar=01;31:*.war=01;31:*.ear=01;31:*.sar=01;31:*.rar=01;31:*.alz=01;31:*.ace=01;31:*.zoo=01;31:*.cpio=01;31:*.7z=01;31:*.rz=01;31:*.cab=01;31:*.wim=01;31:*.swm=01;31:*.dwm=01;31:*.esd=01;31:*.jpg=01;35:*.jpeg=01;35:*.mjpg=01;35:*.mjpeg=01;35:*.gif=01;35:*.bmp=01;35:*.pbm=01;35:*.pgm=01;35:*.ppm=01;35:*.tga=01;35:*.xbm=01;35:*.xpm=01;35:*.tif=01;35:*.tiff=01;35:*.png=01;35:*.svg=01;35:*.svgz=01;35:*.mng=01;35:*.pcx=01;35:*.mov=01;35:*.mpg=01;35:*.mpeg=01;35:*.m2v=01;35:*.mkv=01;35:*.webm=01;35:*.ogm=01;35:*.mp4=01;35:*.m4v=01;35:*.mp4v=01;35:*.vob=01;35:*.qt=01;35:*.nuv=01;35:*.wmv=01;35:*.asf=01;35:*.rm=01;35:*.rmvb=01;35:*.flc=01;35:*.avi=01;35:*.fli=01;35:*.flv=01;35:*.gl=01;35:*.dl=01;35:*.xcf=01;35:*.xwd=01;35:*.yuv=01;35:*.cgm=01;35:*.emf=01;35:*.ogv=01;35:*.ogx=01;35:*.aac=00;36:*.au=00;36:*.flac=00;36:*.m4a=00;36:*.mid=00;36:*.midi=00;36:*.mka=00;36:*.mp3=00;36:*.mpc=00;36:*.ogg=00;36:*.ra=00;36:*.wav=00;36:*.oga=00;36:*.opus=00;36:*.spx=00;36:*.xspf=00;36:';
export LS_COLORS

Randomly Colorful Unix Terminal Prompt

#!/usr/bin/env bash
### ./gen_prompt.sh
### Output: bash script that configures a randomly colorful prompt (PS1).
###   matt.a.feenstra@gmail.com
### For Example:
###   eval $(gen_prompt.sh)

echo 'PROMPT_DIRTRIM=4'

PS_STRING="'\[\033[38;5;$(shuf -i 27-231 -n 1)m\]\u\[\033[38;5;$(shuf -i 27-231 -n 1)m\]@\[\033[38;5;$(shuf -i 27-231 -n 1)m\]\h\[\033[38;5;$(shuf -i 27-231 -n 1)m\]:\[\033[38;5;$(shuf -i 27-231 -n 1)m\]\j\[\033[38;5;$(shuf -i 27-231 -n 1)m\]:\[\033[38;5;$(shuf -i 27-231 -n 1)m\]\w\[\033[38;5;$(shuf -i 27-231 -n 1)m\]\\$\[\033[00m\] '"

echo export PS1=$PS_STRING
 

HOWTO: Use Ruby IO with shell execution (STDIN, STDOUT, STDERR, PID)

# 1. IO.popen

# Runs the specified command as a subprocess; the subprocess's standard

# input and output will be connected to the returned IO object. This

# allows you to provide STDIN input and get STDOUT output easily.

# Asynchronous (IO objects)

# Return: IO object, (IO#pid, IO#read)

# Docs: https://www.rubydoc.info/stdlib/core/IO.popen

io = IO.popen("echo 'hi'") # Or IO.popen(["echo", "hi"])

io = IO.popen(cmd)

IO.popen(["echo", "'hi'"]) do |io|

# ...

end

# 2. open3

# Runs the specified command as a subprocess; the subprocess's standard

# input, stdout, and stderr IO objects are available. There is also

# an "open4" gem to more easily get the PID of the child process.

# Synchronous (get strings) or Asynchronous (IO objects)

# Return: Strings (capture*) or IO objects (popen*)

# Docs: https://docs.ruby-lang.org/en/2.5.0/Open3.html#method-c-popen3

require 'open3'

stdin_io, stdout_io, stderr_io, process_waiter = Open3::popen3(cmd)

stdout_str, stderr_str, process_info = Open3::capture3(cmd)

require 'open4'

pid, stdin, stdout, stderr = Open4::popen4(cmd);

# Extra Advice - Exit Code

# $? which is the same as $CHILD_STATUS (if you require 'english')

# Accesses the status of the last system executed command if

# you use the backticks, system() or %x{}.

# You can then access the ``exitstatus'' and ``pid'' properties

# Docs: https://ruby-doc.org/core-2.7.1/Process/Status.html#method-i-exitstatus

$?.exitstatus

HOWTO: Shell redirection (pipe) and output into Ruby scripts

    Ruby syntax is a little different than most programming languages.  However I have found that it is worth the time and effort required in learning the style.  Here is an easy way to use Ruby and Linux Bash shell seamlessly through redirection, giving a world of capabilities, simply:

$ echo 'stuff' | ruby -e 'puts "this -> #{ARGF.read.chomp} <- is it."'
 

this -> stuff <- is it.
 

$

    Here we see the ARGF constant is assigned data from the left hand side as a String:

 

$ echo 'stuff' | ruby -e 'puts "this -> #{ARGF.read.class} <- is it."'

this -> String <- is it.

$

That's all there is to it!  Hope you've learned something, and I welcome your comments.  Have a great day!

--Matt

HOWTO: Control Spotify and your MacOS volume from the command line

I use the following script called "~/.music.automation.sh" and load it from my "~/.bash_profile" with "source ~/.music.automation.sh".
---

# ~/.music.automation.sh

# Volume stuff
alias vol="osascript -e 'output volume of (get volume settings)'"
alias 0="osascript -e 'set Volume 0'"
alias 1="osascript -e 'set Volume 0.3'"
alias 2="osascript -e 'set Volume 0.6'"
alias 3="osascript -e 'set Volume 0.9'"
alias 4="osascript -e 'set Volume 1.2'"
alias 5="osascript -e 'set Volume 1.5'"
alias 6="osascript -e 'set Volume 1.8'"
alias 7="osascript -e 'set Volume 2.1'"
alias 8="osascript -e 'set Volume 2.4'"
alias 9="osascript -e 'set Volume 2.7'"
alias 10="osascript -e 'set Volume 3.0'"

# Synonyms for above
alias m="osascript -e 'set Volume 0'"


# Spotify stuff
alias next="osascript -e 'tell application \"spotify\" to next track'"
alias n="osascript -e 'tell application \"spotify\" to next track'"
alias previous="osascript -e 'tell application \"spotify\" to previous track'"
alias prev="osascript -e 'tell application \"spotify\" to previous track'"
alias p="osascript -e 'tell application \"spotify\" to previous track'"
alias pp="osascript -e 'tell application \"spotify\" to playpause'"



---
Then, I can SSH into MacOS and control the music remotely, from my phone for example.  Enjoy!

HOWTO: Add loopback as a service

This can be easily done by adding an "ip" command to system startup with RHEL8 "systemctl".

1. Create a run script for ip to setup a loopback device on 192.168.10.1:

echo 'ip addr add 192.168.10.1/24 dev lo' >/usr/local/sbin/loopback2.sh
chmod 700 /usr/local/sbin/loopback2.sh


2. Create the service file:

vi /lib/systemd/system/loopback2.service
or
systemctl edit loopback2


2. Have it start as service with systemctl:


[Unit]
after=network

[Service]
ExecStart=/usr/local/sbin/loopback2.sh

[Install]
WantedBy=default.target


3. Enable and auto start:

systemctl enable loopback2.service
systemctl start loopback2.service


4. Confirm the setup:

ip addr
systemctl status loopback2

HOWTO: PostgresDB & pgAdmin4 setup on RHEL 8

https://yum.postgresql.org

https://yum.postgresql.org/howtoyum.php

---

dnf -y install https://download.postgresql.org/pub/repos/yum/reporpms/EL-8-x86_64/pgdg-redhat-repo-latest.noarch.rpm

dnf install postgresql12-server postgresql12-contrib

---

yum install pgadmin4

/usr/pgadmin4/bin/./pgadmin4-web-setup.sh

service httpd start

Handy UNIX diff: Exclusive match

Super handy tool for selectively removing serial contents from a text file:

#!/bin/bash
# xdiff <new_file> <old_file>
# Exclusive diff - just show what's different from the first file
#       example: xdiff SYMBOLS.txt remove_symbols.txt >SYMBOLS2.out
diff -u $1 $2 | grep '^-[^-]' | sed 's/^-//'

Best prompt ever, Improved!

#!/bin/bash

u_color="\e[38;5;212m"

amp_color="\e[38;5;183m"

h_color="\e[38;5;51m"

col_color="\e[1;34m"

dir_color="\e[1;32m"

ps_color="\e[38;5;226m"

reset="\e[0m"

PS1="$u_color\u$amp_color@$h_color\h$col_color:$dir_color\w$ps_color\$$reset "

echo "PS1=\"$PS1\""