This entire post on Christian’s blog is an absolute goldmine! While I knew most of them, I did learn a few tricks myself! That said, here's one where I find the example a bit lacking:

pushd and popd: If cd - is a toggle switch, pushd is a stack. Need to juggle multiple directories? pushd /etc changes to /etc but saves your previous directory to a hidden stack. When you’re done, type popd to pop it off the stack and return exactly where you left off.

This, to me, slightly undersells the power of pushd/popd combo, and also doesn't mention at all dirs command! From the example above it's not exactly clear how pushd /etc followed by popd is better than just cd /etc followed by cd -. The true power comes when you need to juggle more than one destination! Allow me:

# Build the stack!
pushd ~/Music
pushd ~/Pictures
pushd ~/Sync

# Show the stack
dirs
~/Sync ~/Pictures ~/Music

# Show the stack with numbers
dirs -v
 0  ~/Sync
 1  ~/Pictures
 2  ~/Music

# Switch to another directory (~/Music) in the stack
pushd +2

# Show the stack again
dirs -v
 0  ~/Music
 1  ~/Sync
 2  ~/Pictures

# Remove (pop) entry (~/Sync) from the stack
popd +1

Both pushd and popd can switch or pop in the stack using + or - (I tend to gravitate more towards plus for some reason). No arguments to popd goes in the order as seen via dirs -v until the stack is empty. Quick tip: running pushd ~/some/location by default switches you there immediately—it can be avoided by passing -n flag. You're welcome.

One more expansion:

!!: This expands to the entirety of your previous command. Its most famous use case is the “Permission denied” walk of shame. You confidently type systemctl restart nginx, hit enter, and the system laughs at your lack of privileges.

!! is genuinely clever and I do use it occasionally, but what I use even more often is argument replacement. Like so:

systemctl status nginx
^status^restart

Yes—exactly as you'd expect, it replaces status in the previous command with restart.

Overall, what a great post, thanks for sharing, Christian! 🙌🏻