chore: address shellcheck findings in xrecovery-final.sh

[kojiromike]

Short description of what this resolves:

Address the issues uncovered by shellcheck in one set of (identical) files.

Changes proposed in this pull request:

• Add quotes around variables to avoid accidental wordsplitting and glob expansion.
• Add curly braces around variables for consistency and readability.
• Combine touch to create two files.
• Remove exit 0 to exit with the correct exit code
• Use set -euo pipefail to catch errors earlier.

[jesdynf]

I'm willing to approve this, but can you walk me through how to turn off the carping for unprotected echo statements? That's just being fiddly.

[kojiromike]

can you walk me through how to turn off the carping for unprotected echo statements? That's just being fiddly.

shellcheck doesn't actually seem to care if you quote around echo statements if a variable is not involved. I did those myself, out of habit. I stand by it, though, because echo will have less surprising behavior if its argument is always quoted.

[jesdynf]

I'd prefer not to accept the edits to the echo statements unless we come to a decision that that's a style change we're actually going to enforce going forward, and this minute I'm not planning to do that.

[kojiromike]

Actually the script doesn't work correctly without the quotes. Here's one example from the script:

$ echo xrecovery-final: mysql must not be running, yet it is; aborting
xrecovery-final: mysql must not be running, yet it is
bash: aborting: command not found

It might be barely noticeable since the very next line is exit 1, but it is, in any case, clearly not what the code is intended to do.