TIL: Killing an scp loop

Yesterday I fired off a quick loop to pull down some files from a server:

for f in $(cat file-list.txt); do
  scp user@hostname:path/to/data/$(basename $f) local_dir/
done

I just needed a couple of examples¹ so I decided to kill the command when I had them.

When I closed the shell, I expected everything to stop—but the downloads kept chugging away.

I ran ps aux | grep '[s]cp' and tried kill $PID, but got “no such process.”

Opening htop, I saw the scp process but by the time I grabbed it’s PID, it had finished. I traced the parent with:

ps -o pid,ppid,command -p $(ps aux | grep '[s]cp' | awk '{print $2}')

Examining the parent showed it was /bin/zsh, so I killed that, but the downloads continued.

I traced the grandparent and found it to be login, which worried me because killing that would log me out.

How was this possible?

htop has a nice Tree feature. This is the tree I was climbing:

├─ /Applications/Ghostty.app/Contents/MacOS/ghostty
│  ├─ login
│  │  └─ -/bin/zsh
│  │     └─ scp

So I quit my terminal app (Ghostty.app), and the downloads stopped.

One-liner for fast-moving processes Quickly inspect PID, PPID, command for processes that vanish too fast to track:
```
ps -o pid,ppid,command -p $(ps aux | grep '[s]cp' | awk '{print $2}')
```
htop’s tree mode makes it easy to inspect and kill at the right level of the process tree.
ctrl-D exiting a tab in Ghostty might leave things running as the shell integration by default may not always detect background processes and loops when closing tabs. There are a number of settings to improve this e.g.

shell-integration = zsh
quit-after-last-window-closed = true
wait-after-command = true

Quitting the app should clean these up, as all processes are nested under ghostty.

~/adi