Protip #3: You do want your OpenPGP key to expire

You think you don’t, but you really do.You are probably thinking you don’t want to have to transition to a new key on some arbitrary date. But you can always extend the expiration later. And if you lose your key and don’t have a revocation certificate, the expiration date serves as a kind of “dead man’s switch”. If you don’t prevent it from being triggered by extending the date, your key will be automatically invalidated. This way, if you lose your key (and you don’t have a revocation certificate or have lost that, too), your key will not remain valid forever.

If you use Thunderbird with the Enigmail extension, per my previous tutorial, it is pretty easy to change your key’s expiration date from the Key Management interface. Right-click your key and select Change Expiration Date. Then you can select how many years, weeks, or days it should be until your key expires.

Of course, you will need to re-upload your public key so that your friends can get the extended expiration from the key server. Of course, you can also do the same with GnuPG from the command line, but I’ll leave that as an exercise to the reader.

And now you have no reason to have no expiration date on your keys!

Protip #2: Using loops from the commandline

Remember that the same things you can do in a shell script, you can also do directly from the command line. This includes looping constructs like for, while, and until. In a shell script you might write:

#!/bin/bash
for f in /home/user/Documents/*; do
    new=${f// /-}
    mv "$f" "$new"
done

to rename all of the files in your Documents folder, replacing spaces with hyphens (note that the parameter expansion, ${f// /-}, is not portable). But for something this simple, you don't need to write a script, you can just type this in on the command line, like this:

for f in /home/user/Documents/*
do new=${f// /-}
mv "$f" "$new"
done

or on one line:

for f in /home/user/Documents/*; do new=${f// /-}; mv "$f" "$new"; done

The indentation is irrelevant to the interpreter, we just use indentation in shell scripts for human readability. Those of you who have worked with a programming language with an interactive toplevel, such as Lisp or Python, may recognize how handy this is. Of course, many of you already know this and probably just went, "Duh!", but someone out there either didn't realize they could use loops from the command line, or just didn't really think of it because we usually see them in scripts. That person, upon reading this, was enlightened.¹

Protip #1

Some of you already do this and will think it is comically obvious. But someone out there will read this and think, "Oh, wow... that is such a great idea!"  and it will save them many a headache in the future. That person will achieve enlightenment.

Protip #1:

Whenever you are working on a computer and come across some oddity or have to configure things in an unusual or non-obvious way to make it work, make a note of it and document this information for future use. This will keep you from spinning your wheels trying to solve the same strange problem again later on (you don't think at the time that you will forget this stuff, but you will). One way to do this is to file this information away wherever you store important documents and information. This particularly works well if you maintain a lot of machines and want to keep your records in a centralized location. A simple alternative method (one I really like) is to simply write the information on a note card or something of that nature and put it inside of the case. That way, you can always find it when you are working on that machine.

Upon hearing this, the reader was enlightened.¹