I have a morning routine which would have seemed awfully complicated to the teenaged me, and is probably ridiculously streamlined to the me reading this entry in 2036. One step of it involves recording a number in a spreadsheet.

It started as not-exactly-a-spreadsheet: just a list of numbers which I edited in a text file. Almost immediately I revised it to include dates. After a few months, I realized that I wanted to be able to graph the data, so it became that most rudimentary of spreadsheets, a CSV - comma separated variables.

Some time thereafter I wrote a shell alias to bring up the editor with this particular file, and the next day I changed the alias to send my cursor directly to the last line, which saved me two keystrokes each morning.

There the matter stood for a few years, until this morning. I looked at the file I had just added one line to in the same format as always. I can automate away most of that, said my internal voice.

So I wrote a new shell function which takes the one piece of data from the outside world as an argument and inserts it in the proper format, with the correct date format, as the last line of the spreadsheet. And after verifying that it works, I went back and made the function output the last three lines of the spreadsheet including the new entry, so I could see any fat-fingered mistake immediately.