misc

On rewrites

Most rewrites are mistakes. The rewrites that aren't are the ones where the platform you're built on grew a primitive that subsumes one of your components. The cost of the rewrite is paid; the cost of carrying the old way is paid forever.

Quickly check what's actually in your PATH

I use this one weekly. Splits $PATH on colons, one per line, easy to scan.

echo $PATH | tr ':' '\n'

The Twelve-Factor App ↗

Old, still right. I re-read it whenever I'm about to put config in a YAML file.

Find the largest things on disk

Faster than any GUI disk-usage tool. Pipe it to `head` if you only want the top offenders.

du -h -d 1 . 2>/dev/null | sort -rh

shellcheck saves embarrassment

Every time I add it to a project I find at least one bug I'd already shipped. It is a quiet, free, install-once linter that catches the bash mistakes you didn't know you were making.

On naming

I have spent more hours on names than on the code those names live in. I do not regret a single one. A bad name compounds; a good name pays for itself the first time someone else reads it.

Stop forgetting your EC2 is running

Cron this if you're forgetful about test instances. Stops anything tagged `Env=dev` every night at midnight UTC.

aws ec2 stop-instances --instance-ids \
  $(aws ec2 describe-instances \
      --filters Name=tag:Env,Values=dev Name=instance-state-name,Values=running \
      --query 'Reservations[].Instances[].InstanceId' \
      --output text)

Julia Evans on debugging ↗

If you write software and you haven't read her zines, you're missing one of the kindest debugging educations on the internet.