I just upgraded from 18.04 to 18.10 yesterday, but to my dismay, the new fancy theme, Yaru, was nowhere to be found. Looked around in Gnome Tweaks to no avail. Turns out some of the theme packages were not properly installed, more specifically the yaru-theme-gtk package.
Enter the command apt search yaru-* to see installation status of every package containing “yaru-*”. If they are installed they will state [Installed] inside the square brackets, like so:
If they’re not installed, you can simply fix the issue by running sudo apt install yaru-*. Once complete, log out and back in, and the theme files will be available in Gnome Tweaks.
Voila! Remember to also set Cursor, Icons and Sound theme to Yaru in Gnome Tweaks if desired.
We all love to read log files, and for Linux I tend to simplify that search process if I know what I’m looking for. As you probably know many daemons and programs logs to /var/log , but usually I don’t care to specify the file (like syslog or mysql.err etc) so I just do cat on all the files in the log dir.
So here’s a quick gem to list automated ssh attacks to your server:
Configure ssmtp (sudo nano /etc/ssmtp/ssmtp.conf)  and set correct info for the following lines:
Make aliases for the local user to correct email address 
sudo nano /etc/ssmtp/revaliases
ssmtp uses the local users Full name from the OS as the email sender, so make sure your name is correct. Change by using command sudo chfn -f "John Doe" yourUser
Verify ssmtp works by sending a test mail with command  ssmtp firstname.lastname@example.org
: Example config
# Config file for sSMTP sendmail
# The person who gets all mail for userids < 1000
# Make this empty to disable rewriting.
# The place where the mail goes. The actual machine name is required no
# MX records are consulted. Commonly mailhosts are named mail.domain.com
# Where will the mail seem to come from?
# The full hostname
# Are users allowed to set their own From: address?
# YES - Allow the user to specify their own From: address
# NO - Use the system generated From: address
: Example aliases
# sSMTP aliases # # Format: local_account:outgoing_address:mailhub # # Example: root:email@example.com:mailhub.your.domain[:port] # where [:port] is an optional port number that defaults to 25.
: Example ssmtp test
Subject: Testing ssmtp
enter your body text here
via SMTP server.
Print lines of code (amount) for all .php files in current directory
find . -name '*.php' | xargs wc -l
Show all group memberships for current user
Get username for Apache service
ps aux | grep apache
(Relatively) secure permissions on public html folder for Apache/nginx
The goal is to set root as file owner and add the www-data as group (www-data is the group of the user running apache/nginx). Then, for every user which requires write-permission, simply add them to the www-data group.