Ubuntu Linux setup basics

For username "foo":

$ adduser foo

$ passwd foo

$ sudo usermod -aG sudo foo

$ mkdir -p /home/foo/.ssh

$ cat the_public_key.pem >> /home/foo/.ssh/authorized_keys

$ chown -R foo:foo /home/foo/.ssh

$ chmod 700 /home/foo/.ssh

$ chmod 600 /home/foo/.ssh/authorized_keys

Disable default account:

$ usermod -s /usr/sbin/nologin default_username

Notes:

Not useradd.
Even when logging in with just SSH key, user must have a password. It will only be used for sudo commands.

Sources:

https://unix.stackexchange.com/questions/210228/add-a-user-without-password-but-with-ssh-and-public-key

Sudoers basics

Elasticsearch advanced queries

See also ElasticSearch basics.

DQL to filter by non-zero length: Advert.location_query:* (does not work as a filter)

Or in Lucene: Advert.location_query:?*

Results are limited to 10,000 records, unless you use the scroll API which can paginate and also make parallel requests.

Gist:

MySQL date display format conversion

MySQL date time conversion functions: 

• UNIX_TIMESTAMP(date) docs
• FROM_UNIXTIME(epoch) docs

Examples:

select name, from_unixtime(time_added, '%Y-%m-%d %h:%i')

from company

order by date_added desc

limit 10; -- list the most recently added companies

You may also omit the '%Y-%m-%d %h:%i' format string, to get the default format YYYY-MM-DD HH:MM:SS, e.g. `2023-09-07 09:43:51`

Test2 cheat sheet for Perl

Cheat sheet

Chrome extensions: Download manager reviews

• DownThemAll: Queues, but doesn't intercept
• Thunder Download Manager: Intercepts, but doesn't queue
• Free Download Manager: Just says "Loading..." (on Ubuntu)
• Chrono Download Manager: Intercepts and queues! And resumes. Perfect!

curl -o / wget -O

curl --output file

curl -o file

wget --output-document file
wget -O file

Best to just always use curl, and know it uses lowercase for common arguments like normal.

It's usually already installed as well.

Analyzing HAR files with jq

See gist:

Video processing for fun

Mac

• QuickTime Player
• Edit menu | Add clip after...
• 40 videos, total 250Mb = (Not Responding) & Pinwheel of doom
• 34 videos, total 140Mb = several minutes of editing, then (Not Responding) & Pinwheel of doom
• iMovie
• To download for an older version of MacOS, open App Store | Purchased | Install

Linux

Windows

Web

• wave.video - Really good. Limited to 15 mins.
• More

Android

iPhone

Command-line data processing 2023

Some developer tools with CLI  for processing XML, XHTML, HTML, JSON, YAML, etc.

XML

• xsh (perl - Choroba)
• cpm XML::XSH2
• xsh -P file.xml
• ls
• help ls
• help | less
• <TAB> autocompletion
• xmllint
• xmllint --xpath "//foo" file.xml
• xmllint --shell file.xml
• xmltarlet
• xq (golang - sibprogrammer)
• apt-get install xq
• xq (python - jeffbr13)
• pip install xq

JSON

• jq
• cat file.json | jq . # format
• cat file.json | jq '.[]' # extract array

Search

• fzf
• ripgrep
• ag
• ack
• Doesn't search "binary" files by default
• vim - for searching files

Windows 10 robocopy basics

robocopy c:\temp\source c:\temp\destination /E /DCOPY:DAT /R:10 /W:3

(source)

Running Emby on Linux

wget https://github.com/MediaBrowser/Emby.Releases/releases/download/4.5.4.0/emby-server-deb_4.5.4.0_amd64.deb

sudo dpkg -i emby-server-deb_4.5.4.0_amd64.deb

sudo systemctl status emby-server.service