Linux

Directory Structure

Binaries/packages - /bin, /usr/bin, /usr/local/bin

• /usr/bin is for distribution-managed software packages/programs.
• /usr/local/bin is for software packages that are not managed by the distribution package manager, e.g. locally compiled software.

INFO

See this answer on Stack Exchange: /usr/bin vs /usr/local/bin on Linux

Terminal / Shell

explainshell

explainshell tool to describe part by part a command-line.

write down a command-line to see the help text that matches each argument

Distros

Linux Mint

Install Docker on Linux Mint (21)

As the official documentation for Ubuntu does not cover the case of Linux Mint which somehow behaves differently.

How to Install Docker on Linux Mint 21: A Step-by-Step Guide

Tips and Tricks

Run an executable as a Service

If you are using systemd, it can be used to run an executable in the background as a service.

# Create a service file
sudo vim /usr/lib/systemd/system/my-service.service

Add the following content (generic example)

[Unit]
Description=My Service
After=network.target

[Service]
ExecStart=/path/to/executable

[Install]
WantedBy=multi-user.target

Enable your new service, start it and check its status

sudo systemctl enable my-service
sudo systemctl start my-service
sudo systemctl status my-service

Cheat Sheet

# rsync
# (https://www.digitalocean.com/community/tutorials/how-to-use-rsync-to-sync-local-and-remote-directories)
#
# In short
rsync -az source destination

# Send a file to a remote server
rsync /path/to/source/file username@remote_host:/path/to/destination

# Send a directory to a remote server
rsync -a /path/to/source/directory username@remote_host:/path/to/destination

#  Get a file from a remote server
rsync remote_username@remote_host:/path/to/source/file /path/to/local_destination

# Options:
# -a: archive mode
# -r: recurse into directories
# -P: same as --partial + --progress (keep partially transferred files)
# https://www.digitalocean.com/community/tutorials/how-to-use-rsync-to-sync-local-and-remote-directories#using-other-rsync-options
# > This first flag provides a progress bar for the transfers,
# > and the second flag allows you to resume interrupted transfers:

Server Setup

SSL Certificates with Let's Encrypt and Certbot

One issue that can happen when trying to get a certificate:

sudo certbot --nginx -d yoursite.com -d www.yoursite.com

(Source)

That can give:

Another instance of Certbot is already running.
Ask for help or search for solutions at https://community.letsencrypt.org.
See the logfile /tmp/tmpufwimhau/log or re-run Certbot with -v for more details.

One possible solution here

ps -ef | grep certb

The process ID would be the first number after the user, like: root 5555 5100 … To kill the process, try:

kill 5555

gzip Performance

Improve Website performance (using Nginx)

gzip is a tool for compressing files, that will then be decompressed by the browser.

Configuring Nginx’s gzip Settings

/etc/nginx/nginx.conf

. . .
##
# `gzip` Settings
#
#
gzip on;
gzip_disable "msie6";

gzip_vary on;
gzip_proxied any;
gzip_comp_level 6;
gzip_buffers 16 8k;
gzip_http_version 1.1;
gzip_min_length 256;
gzip_types
  application/atom+xml
  application/geo+json
  application/javascript
  application/x-javascript
  application/json
  application/ld+json
  application/manifest+json
  application/rdf+xml
  application/rss+xml
  application/xhtml+xml
  application/xml
  font/eot
  font/otf
  font/ttf
  image/svg+xml
  text/css
  text/javascript
  text/plain
  text/xml;
. . .

Article from DigitalOcean - How To Improve Website Performance Using gzip and Nginx on Ubuntu 20.04