Check this out to know more about code kata used to hone skills: https://en.wikipedia.org/wiki/Kata_(programming)
ansible
awk
aws
C
C++
cron
curl
cut
df
dig
docker
du
english
find
gcc
gdb
git
Go
grep
httpie
i3wm
idea shortcuts
irssi
java
javascript
jq
lsof
mysql
nc
openssh
openssl
pacman
pmap
popd
ps
pushd
python
rabbitmq
redis
regex
rsync
scp
sed
shellscript
supervisor
systemctl
terraform
tmux
top
vim
vimium
wget
xrandr
zsh
zsh shortcuts
Feel free to suggest theme and propose some exercises